Energy & Vitality
Manage Afternoon Energy Slumps
Feeling flat in the early to mid afternoon is common, and it is mostly a normal dip in the body's daily rhythm that sleep, food, movement, light and drinks can make better or worse. This page is about that mid-afternoon dip; overall daily energy, morning grogginess and long-lasting tiredness have their own pages.
General information, not medical advice. Last updated October 31, 2026. Written by the AlternativeMed editorial team. Not medically reviewed.
Start here
- Protect the night before: a short night makes the afternoon dip stronger, so keep regular sleep times and caffeine in the morning and early afternoon.
- Eat a regular, moderate lunch and drink water with it rather than a very large meal or a sugary snack.
- Move for 5 to 10 minutes after lunch, ideally outside in daylight, instead of sitting through the dip.
Be careful with
- Do not rely on repeated coffee, energy drinks or sugary snacks: caffeine late in the day can disturb sleep, and a sugary snack tends to be followed by more tiredness within about an hour.
- Never drive or use machinery when drowsy; stop somewhere safe.
- If you have diabetes, do not skip meals or change medicines because of tiredness; speak to your care team.
Get help when
- Tiredness that lasts for a few weeks without a clear reason, or affects daily life (NHS advice to see a GP).
- Loud snoring, gasping or choking at night, or falling asleep in the day without meaning to.
- Extreme thirst, passing urine more than usual, weight loss, palpitations, breathlessness or pale skin alongside tiredness.
- Shaking, sweating, a fast heartbeat or confusion, or low mood that does not lift.
About Manage Afternoon Energy Slumps
What this goal means
This goal is about the mid-afternoon dip in energy and alertness, often called the post-lunch dip. A review describes it as a dip in performance during the mid-afternoon hours linked to an increase in sleep propensity at that time of day, and says it is a real phenomenon that can occur even when the person has had no lunch.
The aim is not to switch off a normal rhythm but to make the dip smaller and easier to work with.
1What it can feel like
Common experiences are heavy eyelids, difficulty concentrating, wanting a sweet snack or a coffee, and a slow, foggy feeling a few hours after lunch. For most people it passes; for some it is strong enough to affect work or driving.
1,2What can make it stronger
The research points to a few amplifiers: a short or disturbed night before, a large or high-carbohydrate lunch, alcohol with lunch, long spells of sitting, dim light and mild dehydration. The body clock timing itself is not something to blame on your food choices.
Persistent tiredness is different. The NHS lists common causes such as not enough sleep, an unhealthy lifestyle, stress, depression, hormonal changes, some illnesses and some medicines, and says that unexplained tiredness that continues should be checked.
1,2,3,4,5,6,7Conditions to keep in mind
Conditions that can cause tiredness include sleep apnoea, iron deficiency anaemia, diabetes, an overactive thyroid and ME/CFS, according to the NHS. This page does not diagnose any of them; if the pattern fits, see a clinician and the condition pages linked in Related.
7,8Realistic expectations
Small habits can make a noticeable difference to how the dip feels, but most evidence is from small, short studies, often in healthy young adults after deliberately short nights. Expect a smoother afternoon, not the end of the dip.
The dip may be more likely in some people, such as extreme morning types, according to the review.
1,9Who this applies to
Most adults notice a dip at some point, including office workers, students, parents and drivers. People who are pregnant, older, taking medicines or living with a long-term condition should check with a clinician before changing caffeine, meals or activity, and anyone whose tiredness is heavy or lasting should see one.
7,10Related conditions and symptoms
Anemia and iron deficiency → Vitamin B12 deficiency → Thyroid problems and fatigue → Sleep apnea → Prediabetes, type 2 diabetes and metabolic syndrome → Narcolepsy and hypersomnia → ME/CFS and post-exertional malaise → Insomnia →
A manageable starting plan
An educational starting point, not a personal prescription. Adjust it to your own situation and any advice from your clinician.
Your first actions
- For one week, note the time your energy dips, how you slept, what and when you ate and drank (including caffeine and alcohol), and how long you sat.
- Protect last night's sleep: regular times, a calm wind-down, and caffeine kept to the morning and early afternoon.
- Eat a regular, moderate lunch and drink water with it.
- Build in a 5 to 10 minute walk, ideally outdoors in daylight, after lunch or when the dip starts.
Optional additions
- Try a 10 to 20 minute nap on days after a short night, if you have a quiet place and it does not hurt your night sleep.
- Take an hourly micro-break from sitting.
- If you use caffeine, have it at the start of the dip, not late.
- Swap a sweet snack for water, a walk or a snack with protein or fibre.
What to track
- Time of day and strength of the dip (0 to 10).
- Hours slept the night before.
- Lunch size and what you drank.
- Which change helped most: walk, light, water, nap or caffeine.
When to reassess
Try the changes for about two weeks and look at your notes. A mild dip that eases is a normal pattern. If you are still struggling most days, are falling asleep unintentionally, or the tiredness is spreading beyond the afternoon, see a clinician rather than adding more coffee or supplements.
When to seek professional support
- See a GP if you have felt tired for a few weeks and are not sure why, or tiredness affects daily life (NHS advice).
- Ask about sleep apnoea if you snore loudly or are told you gasp or choke in your sleep.
- People with diabetes should speak to their care team about low blood sugar episodes and meal timing.
- Do not drive or use machinery when drowsy; stop somewhere safe.
What helps
Ordered by how well the research supports each step. Evidence strength is shown on every card; precautions sit next to the advice.
Start here
Protect the night before
Moderate certaintyAddresses: Less pronounced sleepiness in the afternoon
Why it may help: The afternoon dip is a natural feature of the body clock, and a review describes it as worsened by a disturbed night before. Several of the experiments on this page (naps, bright light and a driving simulator) deliberately cut sleep to about 5 hours to make the afternoon dip stronger, which shows how much a short night adds to it. The NHS lists not getting enough sleep or finding it hard to get to sleep as a common cause of tiredness.
How to apply it: Aim for regular sleep and wake times, a calm wind-down and a bedroom that is not too bright, noisy or warm, as the NHS advises. The goal pages on sleep quality and sleep schedules cover this in detail.
Who it may suit: Anyone who is flat in the afternoon after a short or broken night.
Precautions: If tiredness continues despite enough time in bed, loud snoring or gasping at night is a reason to ask about sleep apnoea rather than keep adjusting habits.
7,1,2,9,5,8Improve Your Sleep Quality → Build a Healthy Sleep Schedule → Wake Up Feeling Rested →
Take a short walk or move for a few minutes
Moderate certaintyAddresses: Higher self-rated energy and less fatigue
Why it may help: In a randomized crossover trial of 30 sedentary adults, six hourly 5-minute walks on a treadmill, and a single 30-minute morning walk, each raised self-rated energy and vigor compared with six hours of sitting; only the spread-out walks also improved mood, lowered fatigue and reduced food cravings by the end of the day. In an earlier small study (18 volunteers), a 10-minute brisk walk raised self-rated energy and lowered tension for about 2 hours, more than a candy bar did.
How to apply it: Stand up and walk at an easy pace for 5 to 10 minutes after lunch or when you notice your energy sinking: a lap of the building, a stroll outside, stairs. If you sit for work, set a gentle hourly reminder.
Who it may suit: Desk workers and anyone who sits for most of the afternoon.
Precautions: Both trials were small and short, and the measures were self-rated. Check with a clinician before starting if you have a heart or joint condition or have been inactive for a long time; start gently.
4,11Choose a moderate lunch rather than a very large one
Low certaintyAddresses: Less added drowsiness after eating
Why it may help: A review concluded the post-lunch dip occurs even when no lunch is eaten, but is exacerbated by a high-carbohydrate lunch. In a driving-simulator study of 12 young men who had slept 5 hours, a 922-calorie lunch caused more sleepiness-related lane drifting and more sleepy brain activity than a 305-calorie lunch, with the difference appearing after about 30 minutes. Another study found fat and carbohydrate had different effects depending on whether the meal was eaten mid-morning or at lunchtime, so no single formula is proven.
How to apply it: Eat a regular, balanced lunch of moderate size (for example vegetables or salad, a protein food and a wholegrain or starchy side) and stop when you are comfortable, not stuffed.
Who it may suit: People who feel heavy and sleepy after a large midday meal.
Precautions: The research is small and mostly in healthy young adults. Eating too little can leave you hungry and tired; this page does not suggest skipping lunch. People with diabetes should keep to the meal plan agreed with their care team.
1,2,12,13Fibre, fluids and meal patterns → Food, nutrition and energy →
Additional options
Get bright light and daylight in the afternoon
Low certaintyAddresses: Possibly less sleepiness and steadier alertness
Why it may help: In a laboratory study of 16 healthy adults who had slept 5 hours for two nights, bright light (1,000 lux) from noon to 5 pm reduced subjective sleepiness, reduced slow eye movements and improved reaction-time performance compared with dim light. In a small nap study, 1 minute of 2,000 lux light after a nap had alerting effects comparable with caffeine plus a nap on sleepiness ratings.
How to apply it: Sit near a window, step outside for a few minutes at lunch, or work in a well-lit room rather than a dim one. Daylight outdoors is far brighter than indoor lighting.
Who it may suit: People who spend the day in dim offices or rooms.
Precautions: Both studies were small, in healthy young adults and under laboratory conditions; outdoor light was not tested. Bright light late in the evening can delay sleep, so keep it for daytime.
5,14A planned short nap of about 10 to 20 minutes
Moderate certaintyAddresses: Fewer symptoms of sleepiness for an hour or more
Why it may help: In 24 healthy young adults who had slept about 5 hours, a 10-minute nap at 3 pm improved sleepiness, fatigue, vigor and thinking performance straight away, with some benefits lasting up to 155 minutes. A 20-minute nap helped from about 35 minutes later and the benefit lasted up to 125 minutes. A 5-minute nap did little, and a 30-minute nap caused a period of grogginess before it helped.
How to apply it: If your day allows it, lie or recline somewhere quiet, set an alarm for 10 to 20 minutes and rest; you do not have to fall fully asleep (a study found even dozing helped in drivers). Aim for early afternoon, not late.
Who it may suit: People with a few free minutes and a safe, quiet place, particularly after a short night.
Precautions: The study was small, in good sleepers who were not regular nappers. Long or late naps can make it harder to fall asleep at night; if nights are already poor, check with your clinician. Never nap as a substitute for stopping when drowsy while driving.
9,15Early-afternoon caffeine in a modest amount
Moderate certaintyAddresses: Short-term improvement in alertness and attention
Why it may help: A review found that low to moderate caffeine doses (about 40 to 300 mg) improve alertness, vigilance, attention and reaction time, and that repeated doses help people cope with restricted sleep, though effects on memory and higher-order thinking are less consistent. The US FDA says about 400 mg a day (two to three 12-ounce cups of coffee) is generally not associated with negative effects for most adults, with wide differences in sensitivity.
How to apply it: If you use caffeine, have a coffee or tea around the start of the dip rather than late in the afternoon, and count all sources (energy drinks, some bars, supplements and medicines contain it).
Who it may suit: Healthy adults who tolerate caffeine and do not have trouble sleeping.
Precautions: Caffeine taken 6 hours before bed still disturbed sleep in a home study that used a high 400 mg dose, so late-day coffee can cost you the next afternoon. Limit in pregnancy (NHS advice is no more than 200 mg a day), avoid if you have palpitations or anxiety that caffeine worsens, and talk to a clinician about medicines or heart conditions.
16,10,17,18Drink water through the day
Low certaintyAddresses: Avoiding the tiredness and low concentration that mild dehydration can bring
Why it may help: In a study of 25 young women, losing about 1.4 percent of body weight in fluid, produced by exercise (some also with a diuretic), lowered vigor, raised fatigue and tension scores and worsened concentration and headache, although most thinking tests were not affected. The NHS suggests 6 to 8 cups or glasses of fluid a day as a guide, enough that urine is a pale yellow, and says tea and coffee count.
How to apply it: Keep a glass or bottle of water within reach and have a drink with lunch and again in the middle of the afternoon. Pale yellow urine is a simple check.
Who it may suit: People who forget to drink at work, or who exercise or work in the heat.
Precautions: The dehydration study was small, in young women, and dehydration was caused by exercise. Fluid needs are higher when pregnant, breastfeeding, in hot weather, or when ill. If you have a heart or kidney condition or have been told to limit fluids, follow your clinician's advice.
6,18Take regular micro-breaks
Moderate certaintyAddresses: A small lift in vigor and less fatigue
Why it may help: A meta-analysis of 22 study samples (2,335 people) found short breaks between tasks gave small but statistically significant gains in vigor (d = 0.36) and reduced fatigue (d = 0.35), with no clear effect on overall performance. Longer breaks tended to help more.
How to apply it: Take a few minutes between tasks to stand, stretch, look out of a window or chat, rather than pushing straight through the dip.
Who it may suit: Anyone doing long stretches of focused work.
Precautions: Effects were small, and the studies were mixed in design. Breaks are not a substitute for enough sleep.
19Still being studied
A coffee just before a short nap
Low certaintyAddresses: A stronger effect on afternoon sleepiness than either alone
Why it may help: In a driving simulator study of 12 sleepy volunteers, 200 mg of caffeine plus a nap of under 15 minutes cut sleepiness-related driving incidents to 9 percent of placebo levels, compared with 34 percent for caffeine alone. In a small study of 10 young adults, a 200 mg caffeine dose followed by a 20-minute nap was the most effective option tested for sleepiness and performance for an hour afterwards.
How to apply it: Studies had volunteers take the caffeine just before the nap; caffeine takes a while to act, so people woke as it began to work. This is a research set-up, not a recommendation to repeat daily.
Who it may suit: Possibly people who need to be alert for a short period and can nap.
Precautions: Two very small studies, healthy volunteers, short follow-up. Caffeine too late in the day can disrupt night sleep, and the same cautions on caffeine in pregnancy, heart rhythm problems and anxiety apply.
15,14,17Steady-blood-sugar eating (balanced meals, fewer sugary snacks)
Not enough evidenceAddresses: Not yet shown to prevent afternoon tiredness
Why it may help: A study of 1,070 people wearing glucose monitors found that a dip in blood glucose 2 to 3 hours after a meal predicted hunger and later eating, though only weakly (r = 0.16 for hunger), and it measured hunger rather than tiredness. A meta-analysis of 31 studies found that carbohydrate did not improve mood and was linked to more fatigue and less alertness within the first hour. No trial found for this page shows that a particular lunch prevents the afternoon dip.
How to apply it: Common-sense approaches are regular meals with protein, fibre-rich foods and wholegrains, and fewer sugary snacks, but the benefit for energy is untested.
Who it may suit: Anyone who notices a pattern of sugary snacks followed by a slump.
Precautions: The glucose study was funded by the company that sells the monitoring service, and several authors are employees or consultants. If you have diabetes, do not change meals or medicines without your care team.
20,21,1,13Washing your face after waking from a nap
Low certaintyAddresses: A brief lift in alertness
Why it may help: In a study of 10 young adults, face washing straight after a 20-minute nap showed mild and transient effects but did reduce subjective sleepiness immediately after waking.
How to apply it: Rinse your face with water after a short nap or when you feel foggy.
Who it may suit: People who want a quick, no-cost reset.
Precautions: One small study with short-lived effects.
14Food & nutrition
Lunch and the afternoon dip
A review of the post-lunch dip concluded it is a real feature of the day that can occur even when no lunch has been eaten, and is linked to the body clock's 12-hour rhythm. It is certainly made worse by a high-carbohydrate lunch, according to the same review. So food is not the root cause, but it can change how strong the dip feels.
In a driving-simulator study of 12 young men who had slept 5 hours, a heavier 922-calorie lunch (about three times the fat and twice the carbohydrate) caused more sleepiness-related lane drifting and sleepy brain activity than a 305-calorie lunch, although the two meals did not differ for at least the first 30 minutes. A separate study found that fat and carbohydrate meals had different effects on mood depending on the time of day, and the effect was less evident at lunchtime.
- A moderate-sized, regular lunch is a reasonable aim; the size seemed to matter more than any single food in the study.
- Include vegetables, a protein food and a wholegrain or starchy side for a satisfying meal (general healthy-eating advice; not tested as an afternoon-energy treatment).
- Do not skip lunch to avoid the dip: the review found the dip occurs without lunch.
- If you have diabetes and take insulin or some other medicines, do not skip or delay meals; follow your care team's plan.
Snacks, sugar and blood sugar
In a small study, a candy bar gave an early rise in energy followed about an hour later by higher tiredness and lower energy, while a 10-minute brisk walk gave higher energy and lower tension for about 2 hours. A meta-analysis of 31 studies found that carbohydrate did not improve any aspect of mood and was linked to more fatigue and less alertness within the first hour.
Glucose-monitor research found that dips in blood glucose two to three hours after a meal predicted hunger and later eating, but the link was weak and tiredness was not measured. These dips are normal in people without diabetes. The NHS says true low blood sugar mostly affects people with diabetes on insulin or some other medicines.
- If you want a snack, consider one with protein or fibre, such as nuts, yoghurt or fruit with a handful of seeds (common-sense choice; not tested as an energy treatment).
- Use a short walk or a glass of water before reaching for a sweet snack.
- Shaking, sweating, a fast heartbeat and confusion without diabetes are reasons to speak with a GP.
Drinks
The NHS suggests aiming for 6 to 8 cups or glasses of fluid a day, enough that urine is a pale yellow, and says tea and coffee count. In a study of young women, fluid loss of about 1.4 percent of body weight reduced vigor and increased fatigue and tension.
The FDA says about 400 mg of caffeine a day, roughly two to three 12-ounce cups of coffee, is not generally associated with negative effects for most adults, with big differences between people. The NHS advises no more than 200 mg a day in pregnancy. Alcohol at lunchtime caused more impairment and sleepiness than the same amount in the evening in an experiment with eight women.
- Water with lunch and again mid-afternoon.
- Coffee or tea early in the afternoon rather than late.
- Check labels for caffeine in energy drinks, bars and supplements.
- Keep alcohol for the evening, away from bedtime.
Remedies & supplements
Traditional use, laboratory findings and human trials are kept apart. "Natural" does not mean safe.
Caffeine (coffee, tea)
Moderate certaintyStudied form and route: Drinks; also found in some supplements, bars and medicines
Intended outcome: Short-term boost in alertness; does not replace sleep
Human evidence: A review found that low to moderate doses (about 40 to 300 mg) improve alertness, vigilance, attention and reaction time, and that repeated doses help maintain performance when sleep is restricted. In two small studies, 200 mg of caffeine taken before a short nap reduced afternoon sleepiness more than either alone.
Traditional use: Coffee and tea are traditional daytime drinks in many cultures, often taken after lunch.
Laboratory findings: The review notes caffeine acts by blocking adenosine receptors.
Limits: Effects on memory and decision-making are less consistent. Tolerance and individual sensitivity vary. Caffeine 6 hours before bed disturbed sleep in a home study.
Interactions and precautions: Pregnancy: the NHS advises no more than 200 mg a day. Talk to a clinician if you are breastfeeding, have a heart rhythm problem, anxiety or high blood pressure, or take medicines. Not suitable for children and teens as energy drinks.
Dose, only as reported in studies: Studies used about 200 mg in one dose before a nap. The FDA says up to 400 mg a day is not generally associated with negative effects for most adults.
16,15,14,10,17,18Water and other fluids
Low certaintyStudied form and route: Plain water, tea, milk and other drinks
Intended outcome: Avoids mild-dehydration tiredness
Human evidence: A study of 25 young women found about 1.4 percent body-weight fluid loss lowered vigor and raised fatigue and tension scores.
Traditional use: Not studied for this goal in the sources read.
Laboratory findings: No lab studies reviewed.
Limits: Small study; dehydration was produced by exercise; drinking extra water when already well hydrated has not been shown to add energy.
Interactions and precautions: Follow clinician advice if you have a heart or kidney condition or fluid limits.
6,18Washing your face
Low certaintyStudied form and route: Water on the face after a nap or when drowsy
Intended outcome: A brief wake-up effect
Human evidence: In a study of 10 young adults, face washing after a 20-minute nap suppressed subjective sleepiness straight afterwards, with mild and transient effects.
Traditional use: Not studied in the sources read.
Laboratory findings: No lab studies reviewed.
Limits: One small study; short-lived effect; not a substitute for sleep.
Interactions and precautions: No known risks when using clean water.
14Therapies & care
For an afternoon slump that is mild and passes, self-care is usually enough. If tiredness is heavy, keeps going for weeks or comes with other symptoms, established care starts with finding the cause: the NHS says you may need blood tests to check for anaemia, diabetes or an overactive thyroid, and sleep apnoea needs its own assessment. Treatment depends on what is found and may include talking therapies such as CBT and advice on sleep and relaxing. Never stop a prescribed medicine because of tiredness without speaking to the prescriber.
A GP check and blood tests
Moderate certaintyMedical assessment The NHS advises seeing a GP if you have felt tired for a few weeks and are not sure why, if tiredness affects daily life, or if it comes with other symptoms such as weight loss or mood changes. Tests can check for anaemia, diabetes and hyperthyroidism.
Who it may suit: Anyone whose tiredness lasts weeks, is getting worse or affects daily life.
Precautions: Bring a short diary of sleep, caffeine, meals and medicines.
7Sleep apnoea assessment
Moderate certaintySleep medicine The NHS lists loud snoring, gasping, snorting or choking noises, waking a lot and feeling very tired in the day as symptoms. A GP may refer you to a specialist sleep clinic for tests that can often be done at home.
Who it may suit: People with loud snoring, witnessed breathing pauses or heavy daytime sleepiness.
Precautions: Do not self-treat; ask someone to observe your sleep if you can.
8Talking therapies and sleep or relaxation advice
Moderate certaintyPsychological and lifestyle care The NHS lists talking therapies such as CBT, advice on getting better sleep and advice on relaxing or changing your lifestyle among the possible treatments for tiredness and fatigue, depending on the cause.
Who it may suit: People whose tiredness is linked with poor sleep, stress or low mood.
Precautions: Look for a registered clinician; seek help promptly if you feel low or hopeless.
7Stress, anxiety, burnout and depression → CBT for insomnia →
What to avoid
Habits, products and claims that can get in the way. Never stop a prescribed medicine without talking to the professional who prescribed it.
Risks that apply to most people
Very large lunches
Low certaintyWhy: A driving-simulator study of 12 young men who had slept 5 hours found a 922-calorie lunch caused more sleepiness-related lane drifting and sleepy brain activity than a 305-calorie lunch. A review says a high-carbohydrate lunch exacerbates the post-lunch dip.
Who it applies to: Anyone who feels heavy after a big midday meal, particularly after a short night.
Try instead: Eat a moderate, balanced lunch and have a planned snack later if you get hungry.
2,1Relying on a sugary snack for a pick-me-up
Moderate certaintyWhy: In an 18-volunteer study a candy bar gave a short rise in energy followed about an hour later by more tiredness and less energy, while a 10-minute brisk walk raised energy and lowered tension. A meta-analysis of 31 studies found carbohydrate was linked to more fatigue and less alertness in the first hour after eating.
Who it applies to: Vending machine and sweet-drink habits, especially at 3 pm.
Try instead: Take a short walk, drink water, and if you need a snack choose a food with protein or fibre such as nuts, fruit or yoghurt.
11,21Alcohol at lunchtime
Low certaintyWhy: In eight women, two or four UK units of alcohol with food at 1 pm caused greater reaction-time impairment and sleepiness than the same amounts at 6.30 pm.
Who it applies to: Working lunches, business lunches and weekends.
Try instead: Leave alcohol until the evening, and not within the hours before bed.
3Late-afternoon caffeine
Moderate certaintyWhy: In a home study, 400 mg of caffeine taken even 6 hours before bed disturbed sleep, so a late coffee may feed tomorrow's slump.
Who it applies to: Coffee, tea, cola, energy drinks and caffeine in some supplements, bars and medicines.
Try instead: Keep caffeine for the morning and early afternoon, and have water or a short walk later.
17,10Personal triggers to check
A short or broken night before
Moderate certaintyWhy: A review describes the post-lunch dip as worsened by a disturbed prior night's sleep, and researchers cut sleep to about 5 hours in the nap, light and driving studies on this page to produce a clear afternoon dip.
Who it applies to: Anyone who slept less than usual, a new parent, or someone with night waking.
Try instead: Work on the night first; see the sleep goal pages.
2,9,5Improve Your Sleep Quality → Build a Healthy Sleep Schedule →
Hours of unbroken sitting
Moderate certaintyWhy: In a 30-person crossover trial, six hours of uninterrupted sitting left people with lower energy and vigor than days that included walking, and more fatigue and food cravings than days with hourly 5-minute walks.
Who it applies to: Desk jobs, long meetings, driving and screens.
Try instead: Break up sitting with a few minutes of movement each hour.
4Dim indoor light
Low certaintyWhy: In a laboratory study, daytime dim light was associated with more sleepiness and slower reaction times than bright light after short nights.
Who it applies to: Windowless rooms, dark offices and rooms with blinds drawn.
Try instead: Work near a window or step outside in your break.
5Mild dehydration
Low certaintyWhy: Losing about 1.4 percent of body weight as fluid lowered vigor and raised fatigue and tension scores in 25 young women.
Who it applies to: People who forget to drink, who exercise or who work in heat.
Try instead: Drink fluids regularly; the NHS suggests 6 to 8 cups or glasses a day as a guide.
6,18Products that need caution
Energy drinks and shots
Moderate certaintyWhy: The FDA notes caffeine can be present in many products, that labels vary, and that medical experts advise against energy drinks for children and teens because of sugar and caffeine levels. The sugar load can also feed a later slump (see the sugar snack finding above).
Who it applies to: Anyone drinking more than one a day, teens, and people who are pregnant or sensitive to caffeine.
Try instead: Check the label, count total caffeine from all sources, and try water, a walk or a short nap first.
10,11Supplements marketed for afternoon crashes
Not enough evidenceWhy: No trial in the sources used for this page shows that an energy or adrenal supplement prevents the afternoon dip. Supplements can also contain caffeine, and the FDA says caffeine can appear in dietary supplements.
Who it applies to: Products promising to fix a crash or support the adrenals.
Try instead: Look first at sleep, light, movement, hydration and meal pattern; check any product with a pharmacist.
10Energy supplements and adrenal claims → Medicine interactions →
Unsupported claims
"Sugar gives you energy and then makes you crash"
Moderate certaintyWhy: The meta-analysis found no positive effect of carbohydrate on mood at any time point, and more fatigue and less alertness in the first hour. In the candy bar study tiredness rose about an hour after the initial lift. The pattern is real in small studies but the 'sugar rush' itself was not supported.
Who it applies to: Diet articles and social media.
Try instead: Do not count on sugar for energy; use movement, light, water and sleep.
21,11"The afternoon slump is caused by your lunch"
Moderate certaintyWhy: A review says the post-lunch dip is a real phenomenon that occurs even when the person has had no lunch, and is linked to body-clock biology. Lunch, especially a high-carbohydrate one, can make it worse.
Who it applies to: Common advice to blame a particular food.
Try instead: Treat the dip as normal timing, then manage the amplifiers: short nights, big meals, sitting still.
1,2"A blood sugar crash explains every slump"
Not enough evidenceWhy: The large glucose-monitor study measured hunger and later eating, not tiredness, and the associations were small. NHS says low blood sugar mainly affects people with diabetes who take insulin or some other medicines, and is rare in people without diabetes.
Who it applies to: Glucose monitor marketing and wellness posts.
Try instead: If you have symptoms such as shaking, sweating, a fast heartbeat or confusion, speak to a GP rather than self-diagnose.
20,13"Adrenal fatigue or low cortisol is why you crash at 3 pm"
Not enough evidenceWhy: The review used here links the dip to the 12-hour rhythm in the body clock, not to adrenal problems, and none of the sources read for this page support an adrenal explanation.
Who it applies to: Online tests and supplement marketing.
Try instead: See the claim-check page, and get persistent tiredness checked.
1Common mistakes
Napping too long
Moderate certaintyWhy: In the nap study, a 30-minute nap caused a period of impaired alertness and performance straight after waking (sleep inertia) before benefits appeared, whereas 10 minutes helped at once.
Who it applies to: Anyone who naps.
Try instead: Set an alarm for 10 to 20 minutes and nap early in the afternoon.
9Adding coffee after coffee to push through
Moderate certaintyWhy: Caffeine helps short-term alertness, but a home study found 400 mg taken 6 hours before bed disrupted sleep, which can set up another slump the next day.
Who it applies to: Heavy coffee drinkers with poor sleep.
Try instead: Stay within the FDA's 400 mg a day for most adults (less if sensitive or pregnant) and keep it early.
17,10,16Ignoring slumps that are heavy or getting worse
Moderate certaintyWhy: The NHS says tiredness that continues without an explanation, affects daily life or comes with symptoms such as weight loss, mood changes or gasping and snorting at night is a reason to see a GP, and blood tests may be done for anaemia, diabetes and an overactive thyroid.
Who it applies to: Anyone dozing off during the day or needing naps most days.
Try instead: Keep a short diary and book a check if it persists.
7,8Evidence & safety
What the research shows
The afternoon dip is a well-described feature of the body clock that appears even without lunch and is strengthened by short nights, big or high-carbohydrate lunches and long sitting. Most research on ways to counter it is small and laboratory-based: short naps, bright light, short walks and caffeine each show benefits in studies of 10 to 30 people, and a meta-analysis of micro-breaks found small gains in vigor and fatigue. The popular 'sugar crash' and 'adrenal' explanations are not supported by the studies read for this page, and no trial found shows that a specific lunch or supplement prevents the slump.
Limits of the evidence
- Many studies were small (8 to 30 participants), in healthy young adults, over a few hours, and often after deliberately restricted sleep.
- Several outcomes were self-rated sleepiness or energy rather than long-term health.
- The glucose-dip study measured hunger, not tiredness, and several authors worked for or advised the company that sells the monitoring service.
- The NHS tiredness page was last reviewed in June 2023 and was due a review in June 2026; the advice read is general, not specific to the afternoon.
- Findings on lunch composition are mixed and depend on the time of day and the person.
Precautions and interactions
- Caffeine limits are lower in pregnancy (NHS: 200 mg a day) and need care with heart conditions, anxiety and some medicines.
- Check any supplement with a pharmacist if you take medicines.
- People with diabetes should not change meals or medicines on the basis of this page.
- Tiredness can be a medicine side effect; do not stop a prescribed medicine without advice.
Life-stage considerations
- Pregnancy: tiredness is common; the NHS advises no more than 200 mg of caffeine a day.
- Breastfeeding: talk to your health professional about caffeine, as the FDA advises.
- Teens and children: medical experts advise against energy drinks (FDA, citing the American Academy of Pediatrics).
- Older adults: new or worsening daytime sleepiness should be checked, including medicines and sleep apnoea.
- Shift workers: the body-clock timing of sleepiness differs; see the shift-work sleep page.
Warning signs
- Tiredness lasting weeks with no clear reason, or that affects daily life.
- Loud snoring, gasping, snorting or choking at night, or falling asleep during the day without meaning to.
- Extreme thirst, passing urine more often (particularly at night) and weight loss.
- Palpitations, shortness of breath or pale skin with tiredness.
- Shaking, sweating, a fast heartbeat or confusion.
- Low mood, hopelessness or thoughts of self-harm: seek help promptly from a clinician or local emergency services.
Claim checks
Sugar gives you a burst of energy then a crash
Moderate certaintyThe burst is not supported: a meta-analysis of 31 studies found no mood benefit and more fatigue and less alertness within the hour. A small study did see tiredness rise an hour after a candy bar.
21,11The 3 pm slump is caused by lunch
Moderate certaintyPartly. The dip occurs even with no lunch, but a large, high-carbohydrate lunch can make it worse.
1,2A coffee nap works
Low certaintyTwo small studies found caffeine taken before a short nap reduced sleepiness more than either alone. It is promising but low-certainty and not for late-day use.
15,14Bright light helps afternoon alertness
Low certaintyOne 16-person study found bright light reduced sleepiness and improved reaction times after short nights; more research is needed.
5Blood sugar dips make you tired and hungry
Not enough evidenceDips 2 to 3 hours after meals predicted hunger and later eating weakly; tiredness was not measured.
20Questions people ask
What is the afternoon energy slump?
It is a dip in alertness and energy in the early to mid afternoon, often called the post-lunch dip. A review describes it as a real phenomenon linked to an increase in sleep propensity at that time of day and to the body clock's 12-hour rhythm.
Is it caused by lunch?
Not entirely. The review found the dip can occur even when someone has had no lunch, but a high-carbohydrate lunch makes it worse, and a driving-simulator study found a big lunch increased sleepiness after short sleep.
Should I skip lunch to avoid it?
The research does not support that. The dip happens without lunch, and skipping meals can leave you hungry and tired. People with diabetes should not skip or delay meals.
Does a sugary snack help?
Not for long. A small study found energy rose briefly and then tiredness increased about an hour later, and a meta-analysis found carbohydrate was linked to more fatigue and less alertness in the first hour.
How long should a nap be?
In a study of 24 young adults after a short night, 10 minutes gave the best overall results, 20 minutes helped later and for longer, and 30 minutes caused grogginess first. Nap early in the afternoon, and not when you need to drive.
Does coffee help?
Caffeine improves alertness in the short term. Use it early in the afternoon, count all sources, and keep to about 400 mg a day or less for most adults (FDA), or 200 mg in pregnancy (NHS). Caffeine 6 hours before bed disturbed sleep in a home study.
Is the afternoon crash low blood sugar?
Usually not. The NHS says low blood sugar mainly affects people with diabetes who take insulin or some other medicines and is rare in people without diabetes. If you get shaking, sweating, a fast heartbeat or confusion, see a GP.
Can drinking more water help?
Mild dehydration lowered vigor and raised fatigue in one study of 25 young women, so drinking regularly makes sense. The NHS suggests 6 to 8 cups or glasses of fluid a day as a guide.
Does a walk really help?
Small trials suggest so. Five-minute walks each hour raised self-rated energy and cut fatigue compared with sitting all day, and a 10-minute brisk walk raised energy for about 2 hours in a small study.
Do supplements prevent afternoon crashes?
The sources read for this page include no trial showing this. Some contain caffeine. See the energy supplements claim-check page and ask a pharmacist before using any if you take medicines.
When should I see a doctor?
The NHS suggests seeing a GP if you have been tired for a few weeks and are not sure why, if it affects daily life, or if it comes with other symptoms such as weight loss, mood changes, or gasping or snorting at night.
Is this page medical advice?
No. It summarises published research and public health guidance in plain language and does not replace advice from your own clinician.
References
- Monk TH. The post-lunch dip in performance. Clin Sports Med. 2005. PMID 15892914. source
- Reyner LA, et al. 'Post-lunch' sleepiness during prolonged, monotonous driving - effects of meal size. Physiol Behav. 2012. PMID 22155490. source
- Horne JA, Gibbons H. Effects on vigilance performance and sleepiness of alcohol given in the early afternoon ('post lunch') vs. early evening. Ergonomics. 1991. PMID 2009851. source
- Bergouignan A, et al. Effect of frequent interruptions of prolonged sitting on self-perceived levels of energy, mood, food cravings and cognitive function. Int J Behav Nutr Phys Act. 2016. PMID 27809874. source
- Phipps-Nelson J, et al. Daytime exposure to bright light, as compared to dim light, decreases sleepiness and improves psychomotor vigilance performance. Sleep. 2003. PMID 14572122. source
- Armstrong LE, et al. Mild dehydration affects mood in healthy young women. J Nutr. 2012. PMID 22190027. source
- NHS. Tiredness and fatigue. Page last reviewed 2 June 2023. Read 2026-10-31. source
- NHS. Sleep apnoea. Page last reviewed 11 May 2026. Read 2026-10-31. source
- Brooks A, Lack L. A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative? Sleep. 2006. PMID 16796222. source
- US Food and Drug Administration. Spilling the Beans: How Much Caffeine is Too Much? Content current as of 28 August 2024. Read 2026-10-31. source
- Thayer RE. Energy, tiredness, and tension effects of a sugar snack versus moderate exercise. J Pers Soc Psychol. 1987. PMID 3820066. source
- Wells AS, Read NW. Influences of fat, energy, and time of day on mood and performance. Physiol Behav. 1996. PMID 8737894. source
- NHS. Low blood sugar (hypoglycaemia). Page last reviewed 3 August 2023. Read 2026-10-31. source
- Hayashi M, Masuda A, Hori T. The alerting effects of caffeine, bright light and face washing after a short daytime nap. Clin Neurophysiol. 2003. PMID 14652086. source
- Reyner LA, Horne JA. Suppression of sleepiness in drivers: combination of caffeine with a short nap. Psychophysiology. 1997. PMID 9401427. source
- McLellan TM, Caldwell JA, Lieberman HR. A review of caffeine's effects on cognitive, physical and occupational performance. Neurosci Biobehav Rev. 2016. PMID 27612937. source
- Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013. PMID 24235903. source
- NHS. Water, drinks and hydration. Page last reviewed 17 May 2023. Read 2026-10-31. source
- Albulescu P, et al. 'Give me a break!' A systematic review and meta-analysis on the efficacy of micro-breaks for increasing well-being and performance. PLoS One. 2022. PMID 36044424. source
- Wyatt P, et al. Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nat Metab. 2021. PMID 33846643. source
- Mantantzis K, et al. Sugar rush or sugar crash? A meta-analysis of carbohydrate effects on mood. Neurosci Biobehav Rev. 2019. PMID 30951762. source
Related on AlternativeMed
Related goals
Have More Energy Throughout the Day → Feel More Energetic in the Morning → Understand & Address Persistent Tiredness → Improve Your Everyday Stamina → Reduce Mental Fatigue → Support Energy Through Nutrition → Stay Hydrated for Daily Wellbeing → Balance Activity & Rest → Manage Energy Without Relying on Stimulants → Improve Your Sleep Quality → Build a Healthy Sleep Schedule →
Ingredients, foods and supplements
Research, safety and claim-check resources
Fatigue: when to get help → Energy supplements and adrenal claims → Everyday habits for energy → Energy and vitality research and evidence → Fatigue from medicines, mood and other conditions → Cortisol and 'adrenal fatigue' → Caffeine, alcohol and sleep → Fibre, fluids and meal patterns → Sleep hygiene → Stress, anxiety, burnout and depression → Medicine interactions →