In a new class I teach at Stanford called "Eat Well for Life," I was asked to describe foods that could help with sleep. This is an interesting question because many other considerations--like too much stress, too little exercise, and psychological factors--play a big role in insomnia. None-the-less, there is scientific evidence that certain dietary components may play a role in promoting a good night's sleep, or preventing it.

What to Avoid
The link between food and sleep is as much about what you don't do as what you do. The general guidelines are:

Avoid caffeine after 3 pm.
Avoid heavy meals after 7 pm.
Avoid alcohol, especially in the late afternoon and evening.

What to Try

Try Tryptophan
The age-old advice to drink warm milk at night is based in science. Milk contains an amino acid called tryptophan which is converted into serotonin (a feel-good hormone) and melatonin (which regulates the sleep-wake cycle). Tryptophan is found in a lot of foods including chamomille tea and turkey, but I don't recommend eating a turkey leg before bedtime. Some studies show that consuming more tryptophan at both breakfast and dinner can increase total sleep time and sleep efficiency (1, 2).

Try Glycine
Glycine is an amino acid found in protein-rich foods like meat, dairy, fish, and eggs. It acts as a neurotransmitter with an ability to both stimulate the central nervous system and calm it down. Recent research shows that a supplement of 3 mg at night can help you fall asleep more quickly and reduce symptoms of insomnia (3). It does this by slightly reducing body temperature and increasing serotonin levels. If you decide to try this option, make sure to talk to your healthcare provider as glycine can interfere with some medications. (You'll also need to order it on-line as glycine is not available in traditional drug stores.)

What About Melatonin?
Melatonin has received a lot of press in recent years as a sleep aid, but the data are mixed about its impact. Melatonin is a hormone released by the brain when it starts to get dark and plays a key role in the sleep-wake cycle. Melatonin supplements are especially helpful for jet lag, or if you are a shift worker and need to sleep during the day. In these cases, your body can't produce melatonin because it is light outside. Melatonin may be less effective for those of us with normal exposure to light and dark.