What to know about foods that keep you awake

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Caffeine is a drug that stimulates the central nervous system. Many people consume caffeine, for example, in the form of coffee, to help them wake up in the morning. Caffeine is also present in chocolate, tea, energy drinks, and soda, such as cola.

A 2017 systematic review combined evidence from several clinical trials and found that caffeine prolongs the time it takes to fall asleep, reduces total sleep time, and worsens sleep quality. Additionally, the substance increases wakefulness and arousals. Some individuals are also more sensitive to caffeine’s effects due to genetic differences, with older adults being more prone than younger adults.

Although some studies have shown health benefits from moderate doses of caffeine, the Food and Drug Administration (FDA) has recommended that healthy adults limit their consumption to less than 400 milligrams (mg) per day, the equivalent of 4–5 cups of coffee.

Consuming caffeine in excess can cause nausea, dizziness, dehydration, headaches, restlessness, rapid heartbeat, insomnia, and anxiety. Additionally, the Centers for Disease Control and Prevention (CDC) recommend that people with insomnia avoid caffeine.

Although alcohol is a depressant, it does not promote restful sleep. Although some people may fall asleep quickly after consuming alcohol, they often find themselves waking up earlier than usual and struggling to go back to sleep.

Alcohol also interferes with the circadian rhythm, worsening sleep quality. It can also negatively affect sleep apnea.

A review of studies in 517 healthy adults confirmed the negative effects of alcohol on sleep. It found that although alcohol may reduce the time a person needs to fall asleep, it significantly disrupts rapid eye movement (REM) sleep, particularly in the second half of sleep. People require quality REM sleep for sufficient rest.

Furthermore, the CDC recommends abstaining from alcohol before bedtime.

A 2019 study of 440 medical students reports that spicy foods may negatively affect sleep in several ways. They can cause indigestion, acid reflux, and heartburn, making it uncomfortable to lie down. Additionally, acid reflux can worsen sleep apnea. These foods also raise body temperature, making it difficult to get cool enough to fall asleep comfortably.

The tolerance for heat from chili peppers, within in many spicy foods, and its effects on the body, varies from individual to individual. For those people who find that consuming spicy foods negatively affects sleep, it may be best to avoid eating them in the hours before bedtime.

Foods that cause a spike in blood sugar, such as white rice, potatoes, candy, and other sugary foods, are called high glycemic (GI) foods.

Consuming these foods causes blood sugar to rise rapidly, resulting in the release of insulin, which affects tryptophan and serotonin levels. There is also a complex interaction of insulin with adrenalin, cortisol, glucagon, and growth hormone, all of which can negatively impact sleep.

Research seems to indicate that eating too many of these foods can contribute to insomnia. It can also increase inflammation in the body and alter intestinal bacteria. Eating too many of these foods can also increase inflammation in the body and alter gut bacteria. Additionally, a large 2020 study found a link between intake of high GI foods and insomnia in postmenopausal women across a 3-year period.

Consuming high fat content foods, such as fatty meats and desserts, may also disrupt sleep. The body’s digestion naturally slows when a person goes to sleep. Fatty foods will cause the stomach to feel full and may make it difficult for individuals to feel comfortable. They can also cause indigestion and acid reflux, which are also likely to result in poor sleep quality.

In a study of 440 medical students, higher fat intake had links to shorter total sleep time, less restorative sleep, and more sleep disruption. Another smaller 2016 study in 26 healthy adults also found that consuming a diet high in saturated fat had associations with lighter, less restorative sleep.

However, a much larger cohort study in men found an association between higher levels of trans fats and probable insomnia. A review of epidemiological studies found similar results.

Highly processed foods include fast food and prepackaged foods. While convenient, these foods contain many of the nutritional components above, including sugars and fats, which negatively impact sleep.

In a 2020 study of approximately 2,500 young adults, researchers found that higher consumption of processed foods shares significant links with poor sleep quality.

Additionally, 2018 research found that highly processed foods cause shorter durations of sleep and poor sleep quality in children aged 12–18 years.

Many foods have associations with negative effects on sleep. Some of the more common ones include caffeine, alcohol, spicy foods, high GI foods, fatty foods, and processed foods.

Being aware of these types of foods and avoiding them close to bedtime can improve the chances of good sleep.

Adequate quality sleep is important for reducing the risk of numerous health complications.

When eating before bedtime, health experts recommend choosing foods that help promote sleep.

Learn more about foods that promote good sleep.