What you eat affects how you sleep. One of the keys to a restful night’s sleep is to get your brain calmed rather than revved up. Some foods contribute to restful sleep; other foods keep you awake. We call them sleepers and wakers. Sleepers are tryptophan-containing foods, because tryptophan is the amino acid that the body uses to make serotonin, the neurotransmitter that slows down nerve traffic so your brain isn’t so busy. Wakers are foods that stimulate neurochemicals that perk up the brain.
Tryptophan is a precursor of the sleep-inducing substances serotonin and melatonin. This means tryptophan is the raw material that the brain uses to build these relaxing neurotransmitters. Making more tryptophan available, either by eating foods that contain this substance or by seeing to it that more tryptophan gets to the brain, will help to make you sleepy. On the other hand, nutrients that make tryptophan less available can disturb sleep.
Eating carbohydrates with tryptophan-containing foods makes this calming amino acid more available to the brain. A high carbohydrate meal stimulates the release of insulin, which helps clear from the bloodstream those amino acids that compete with tryptophan, allowing more of this natural sleep-inducing amino acid to enter the brain and manufacture sleep- inducing substances, such as serotonin and melatonin. Eating a high-protein meal without accompanying carbohydrates may keep you awake, since protein-rich foods also contain the amino acid, tyrosine, which perks up the brain.
To understand how tryptophan and carbohydrates work together to relax you, picture the various amino acids from protein foods as passengers on a bus. A busload containing tryptophan and tyrosine arrives at the brain cells. If more tyrosine “passengers” get off the bus and enter the brain cells, neuroactivity will rev up. If more tryptophan amino acids get off the bus, the brain will calm down. Along comes some insulin which has been stalking carbohydrates in the bloodstream. Insulin keeps the tyrosine amino acids on the bus, allowing the brain-calming tryptophan effect to be higher than the effect of the brain-revving tyrosine.
You can take advantage of this biochemical quirk by choosing protein or carbohydrate-rich meals, depending on whether you want to perk up or slow down your brain. For students and working adults, high protein, medium-carbohydrate meals are best eaten for breakfast and lunch. For dinner and bedtime snacks, eat a meal or snack that is high in complex carbohydrates, with a small amount of protein that contains just enough tryptophan to relax the brain. An all- carbohydrate snack, especially one high in junk sugars, is less likely to help you sleep. You’ll miss out on the sleep-inducing effects of tryptophan, and you may set off the roller-coaster effect of plummeting blood sugar followed by the release of stress hormones that will keep you awake. The best bedtime snack is one that has both complex carbohydrates and protein, and perhaps some calcium. Calcium helps the brain use the tryptophan to manufacture melatonin. This explains why dairy products, which contain both tryptophan and calcium, are one of the top sleep-inducing foods.