How Diet Affects Sleep

Sleep comprises one-third of our day—or at least it should. There is no longer any doubt that sleep plays an integral role in mental and physical health. Unfortunately, too many factors negatively influence sleep, including mental states such as anxiety and depression, disease state, drug side effects, time since the last sleep episode, the contents of one's diet, and many common drugs.

Source: BDS Piotr_Marcinski Shutterstock

What you eat before bedtime might improve your chances of getting a good night’s sleep—and recent research suggests that eating something sweet might help induce drowsiness. Elevated blood sugar levels have been shown to increase the activity of neurons that promote sleep. One recent study showed that sleep onset latency, the time it takes to fall asleep, was significantly reduced after the consumption of high-glycemic-index meals four hours before bedtime. This is related to your brain’s significant requirement for sugar in order to maintain normal function.

Meal Timing Matters

Recent studies have investigated the influence of circadian rhythms on metabolic processes. Consuming a meal less than two hours before sleep time or consuming a major percentage of the daily calories late in the day can greatly impair sleep quality. Essentially, eating too many calories at the end of one’s biorhythm can induce the gut microbiota to produce a pro-inflammatory state that disrupts your circadian rhythm and sleep quality.

It truly does matter when you eat. Our circadian rhythm determines the most efficient timing for food digestion and metabolism. The take-home message from both animal and human studies is to eat a big breakfast, eat a small dinner, and never have late-night snacks.

Skipping breakfast and then overeating in the evening play a significant role in weight gain and obesity. Furthermore, people who skip breakfast report not feeling as satisfied by their food and being hungry between meals.

This is your new mantra for better sleep: Eat breakfast like a king, lunch like a prince, and dinner like a pauper.

Obesity and Sleep

A bidirectional relationship exists between obesity and sleep. Short sleepers often make poor nutritional choices and tend to have higher caloric intakes compared to people who sleep more than seven hours each night.

Short sleepers, defined as people who sleep less than seven hours each night, tend to consume a less diverse selection of foods with lower protein and fiber intake than those sleeping more hours. People who sleep very few hours each night tend to snack more often, particularly on high-fat foods, and become obese.

Why? People who go to bed late each night tend to crave high-glycemic-index foods in the evening hours due to increased ghrelin levels and decreased leptin levels.

Sleep-Promoting Nutrients

Melatonin influences sleep quality. Melatonin is secreted by the pineal gland about two hours before bedtime. Melatonin helps to initiate sleep and, for some people, is an effective treatment for insomnia.

Studies have shown that taking melatonin before bedtime can significantly improve sleep quality and decrease sleep onset latency in insomnia without the morning-after grogginess. It may be possible to boost melatonin levels through diet by consuming certain plants, mushrooms, and some fruits such as pineapples, cherries, grapes, oranges, and bananas.

Consuming fresh tart cherry juice, for example, effectively reduced sleep latency and improved insomnia in older subjects. Urinary melatonin concentrations were elevated after consuming tart cherries.

Kiwifruit is also known to help promote better sleep. Consuming two kiwis an hour before bedtime increased total sleep time and sleep quality. Kiwis are a source of folate, which, when deficient, is related to insomnia.

Sleep Essential Reads

Hot Weather Is Linked to Sleepiness in Fruit Flies, Too

Should You Sleep With Your Spouse?

A high intake of fish and vegetables also has a positive effect on sleep. Fatty fish is rich in vitamin D and omega-3 fatty acids. Vitamin D deficiency is associated with sleep disorders, while omega-3 fatty acids are associated with positive sleep outcomes. Curcumin found in turmeric can increase non-rapid eye movement sleep via its ability to block histamine H1 receptors. Compare this action to how typical over-the-counter sleep aids work by blocking histamine receptors.

Consumption of a Mediterranean diet has been associated with improved sleep outcomes in various populations, from teenagers to older adults. In contrast, a study on middle-aged women found that a high intake of high glycemic index foods and a lack of vegetables in the diet was associated with poor sleep quality.

Sleep-Impairing Nutrients

Caffeine is an adenosine-receptor antagonist that increases arousal, wakefulness, and alertness. Daytime consumption decreases the main metabolite of melatonin, 6-sulfatoxymelatonin, at night, which disrupts the circadian rhythm and negatively affects sleep onset and quality.

Nicotine can increase sleep latency and sleep fragmentation and decrease sleep efficiency and quality. Similarly, alcohol consumption prior to sleep leads to decreased sleep onset latency, disrupted normal sleep architecture, poor sleep quality, and increased sleep fragmentation and nighttime awakenings, culminating in reduced total sleep time. Alcohol consumption before bed often leads to more emotional dreaming during the early morning.

The take-home message is that almost everything that we consume, whether drugs or nutrients, can affect brain function, the quality of our sleep, and daytime cognitive function.