Food and sleep: what the evidence says

In a placebo-controlled study, a moderate dose of caffeine taken at bedtime, three hours before or six hours before all disturbed sleep compared with placebo. The authors concluded that the trial supports avoiding substantial caffeine for at least six hours before bed Drake 2013. Coffee is the obvious source, but strong tea, cola, energy drinks, pre-workout powders and dark chocolate add up too. Green tea has less caffeine than coffee but is not caffeine-free.

Alcohol works the other way round. A review of the sleep-laboratory studies found that at every dose it shortens the time to fall asleep and deepens the first half of the night, then increases disruption in the second half, and it delays and reduces REM sleep at moderate and higher doses Ebrahim 2013. A nightcap can feel like it helps while making the night worse.

The American College of Physicians recommends that all adults with chronic insomnia receive CBT-I as the initial treatment, rated a strong recommendation on moderate-quality evidence Qaseem 2016. The American Academy of Sleep Medicine guideline on behavioral and psychological treatments also puts multicomponent CBT-I first Edinger 2021. CBT-I is a short, structured program (in person, by phone or through a digital program) covering sleep timing, time in bed, and the thoughts and habits that keep insomnia going.

Loud snoring broken by silent pauses and gasps, or waking unrefreshed and sleepy all day, points to obstructive sleep apnea, which needs a medical assessment rather than a diet changeMedlinePlus.

MedlinePlus sleep-habit advice adds the basics: keep the bedroom quiet, dark and at a temperature you like, and if you cannot fall asleep within 30 minutes, get up and do something quiet elsewhere until you feel sleepy MedlinePlus.

The foods most often suggested for sleep are tart cherry juice, chamomile tea and warm milk. The table on this page shows how each one is graded. In short, the trials are small, short and often unblinded, and none comes close to the effect of CBT-I. A caffeine-free herbal infusion as part of a wind-down routine is a reasonable habit; just keep the cup small if night-time trips to the bathroom wake you.

Magnesium is the supplement most often sold for sleep. The evidence is weak: a 2021 systematic review found only three small trials in 151 older adults, at moderate to high risk of bias, and judged the evidence of low to very low quality Mah 2021. Pooled, people fell asleep about 17 minutes sooner, and the change in total sleep time was not statistically significant.

Food comes first. Good sources include dark leafy greens, nuts such as almonds and cashews, beans and peas, seeds, tofu and whole grains MedlinePlus. The recommended daily amount for adults is 310 to 320 mg for women and 400 to 420 mg for men, depending on age MedlinePlus. For supplements, the NIH Office of Dietary Supplements sets an upper limit of 350 mg a day of supplemental magnesium for adults, because higher supplement doses can cause diarrhea, nausea and cramping NIH ODS. People with reduced kidney function can build up magnesium to harmful levels and should not take supplements without their clinician MedlinePlus.

If your clinician suggests trying a supplement, USA Magnesium sells a single product, magnesium glycinate. Check the dose per serving against the 350 mg limit.