Everyone knows that coffee after dinner can interfere with sleep. But what about other foods that derail a full night’s rest?
Research shows that there are two ways what you eat can affect sleep:
1. Specific foods such as caffeine can impair sleep
2. General nutrition habits can reduce the quality of your sleep
Under category #1, we’ve got anything containing caffeine, including coffee, energy drinks, chocolate, soda, and in some cases tea. Green and black tea contain caffeine, however, green tea also provides theanine, the main amino acid that is in tea leaves, which has significant anti-stress effects and can improve sleep. For example, one study found that a low-caffeine green tea reduced stress and improved sleep quality compared to standard green tea. Herbal tea containing chamomile, valerian, or passionflower may also improve sleep.
Alcohol is often incorrectly believed to improve sleep, but studies show even a small drink can inhibit a good night’s rest, causing a person to wake up a few hours after imbibing.
Sugar can make you hyper by spiking blood sugar followed by a crash that may lead to fatigue. The overall effect on sleep is negative: A diet high in sugar makes you prone to micro-awakenings, causing lighter sleep. Sugar may also lead you to wake up hungry as insulin and blood sugar drop.
Saturated fat, often found in junk food, results in less deep, restorative sleep, that helps with memory consolidation.
Spicy foods can also impair sleep by causing indigestion or heartburn. Digestive problems and heartburn can be worse when lying down, making dreamland almost impossible to achieve.
Foods containing lots of water such as watermelon or celery are natural diuretics that push water through your system and may have you waking up for bathroom trips.
Under category #2, a typical western diet that is high in processed foods, sugar, and fat will do your sleep no favors. Not only is this dietary profile linked to more awakenings at night, it has implications for the day following a poor night’s rest. When people are sleep deprived they increase their food intake the next day by as much as 300 calories and are more likely to choose unhealthy, “hedonistic” foods that make them feel good temporarily.
Although eating healthy carbs at night may improve sleep by raising the calming, feel good neurotransmitter serotonin, a high-carb diet is linked to more awakenings and a worse night’s sleep than one that is higher in protein.
Interestingly, although protein is generally considered energizing as amino acids stimulate areas of wakefulness in the brain, studies don’t show that it will impair sleep. In fact, healthy higher protein diets appear to be linked with better rest and most research shows that pre-bedtime protein supplementation will not keep you up.
Why are sleep and nutrition so intricately related?
Both sleep and wakefulness are controlled by a series of chemical reactions in the body that regulate your circadian rhythm. Certain nutrients affect them to alter how long it takes you to fall asleep, how often you wake up during the night, and how you feel the next day.
For example, we typically think of cortisol as a stress hormone, but it is also a metabolic hormone that is released as blood glucose drops. Skipping meals, or eating a diet high in refined carbs, will lead to blood sugar irregularities and elevated cortisol. A day of poor eating and non-stop stress means cortisol will be elevated at night, impairing sleep. Fortunately, certain foods can help offset this, counteracting that jittery, depleted feeling so that you are able to recover with a decent night’s rest.
Lindseth, G., et al. Nutritional Effects on Sleep. Western Journal of Nursing Research. 2013. 35:497–513.
Unno, K., et al. Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content. Nutrients. 2017. 9(7), 777.