Reishi for Sleep and Stress: What Trials Found

Short answer. For sleep, proper evidence from human trials was not found in the sources we searched. For stress and mood there are a few small trials with mixed results. Animal studies on sleep exist, but they cannot tell us what happens in people.

Safety first. Memorial Sloan Kettering Cancer Center (MSK) lists insomnia and nausea among possible side effects of reishi, so a product taken to help sleep may do the opposite for some people. [1] Liver injury has also been reported; see reishi side effects and liver injury reports. Anyone who takes sedatives or sleep medicines, is pregnant or breastfeeding, or has a long-running sleep problem should ask a pharmacist or clinician before using any reishi product. See medicine interactions.

Which reishi? Names and forms

"Reishi" (Japanese) or "lingzhi" (Chinese) usually means woody Ganoderma mushrooms. The GBIF database lists Ganoderma lucidum (Curtis) P.Karst. as an accepted species and Ganoderma lingzhi as a synonym of Ganoderma sichuanense. [2] The National Cancer Institute (NCI) notes that most research worldwide was published under the name G. lucidum. [3] Trials below used different materials (fruiting body powder, extracts, a polysaccharide extract), and a result for one does not carry over to another. See reishi species, spores, fruiting body and mycelium products.

Traditional use (not proof)

Traditional use only. MSK says reishi holds an important place in the traditional medical systems of China, Japan, Korea and other Asian countries. [1] The authors of one rat study describe it as used in China for hundreds of years as a tranquilizing agent for restlessness, insomnia and palpitation. [4] That is a description of tradition. It does not show that a supplement works, and research is not dismissed because a use is traditional. See reishi and cordyceps in Chinese medicine.

What human studies found

MSK's summary also says clinical studies indicate lower anxiety, but we did not read the study it cites for that statement. [1] Because the studies we read were small, short and used different products, we cannot say that reishi relaxes people or improves sleep.

Animal findings (preclinical, not human evidence)

In mice and rats, several reishi preparations shortened the time to fall asleep or lengthened sleep. Examples include a mycelium alcohol extract in mice for 28 days [10] and a fruiting body extract in rats over three days. [4] One rat study suggested a benzodiazepine-like effect, at least in part. [11] A mouse study concluded the effect depends on how an extract is prepared and administered. [12] These results come from animals given other amounts by other routes. They are a reason to run human trials, not a result for people.