Caffeine is the most commonly used psychoactive substance in the world. It is consumed daily by 75% of Americans. While it is a proven mood booster, surprisingly little research has examined the effects of caffeine on sleep.
Caffeine is often consumed near bedtime to increase alertness or cope with sleepiness. This behavior may be problematic as caffeine can negatively impact sleep onset and quality, potentially increasing daytime sleepiness.
Caffeine is a sedative that induces sleeplessness. In large amounts, it can also cause mental problems and irregular heartbeats. It is found in chocolate, tea, coffee, soft drinks, energy drinks, and prescription medications such as drugs for colds and coughs.
It is also added to over-the-counter allergy medications (antihistamines), painkillers (opioids), and antidepressants. These pills have varying levels of caffeine. Caffeine’s half-life varies from person to person, so how it affects some people may differ from others.
Coffee is an all-American beverage. It’s a part of our national identity and has been for centuries. It’s also one of the most widely consumed beverages globally, trailing only water and tea.
Coffee is rich in caffeine, dramatically affecting your brain and body.
The effects of caffeine on sleep differ from person to person, depending on how much caffeine you consume and your sensitivity to it. Some people may be more sensitive than others because of their genes or other age, or physical health factors.
Some of the effects of caffeine include:
- Caffeine is a stimulant that acts as a psychoactive drug. It promotes arousal by increasing dopamine levels in the brain and blocking adenosine, making you feel more alert.
- Caffeine can have many short-term and long-term effects on sleep. It can disrupt sleep by delaying its onset and reducing the time spent in REM (rapid eye movement) sleep — a phase when people are most likely to dream.
- Caffeine has been shown to interfere with deep sleep stages 3 and 4 (slow-wave sleep) during the first half of the night and REM sleep during the second half of the night. In addition, it reduces slow-wave sleep early in the night when needed most for memory consolidation, learning, and creativity.
- Caffeine may help promote wakefulness in people who don’t consume enough calories during the day. Still, eating enough calories — especially carbohydrates — can cause rebound fatigue by interfering with regular sleep cycles when it wears off several hours later at night.
- Caffeine acts as a central nervous system stimulant, increasing alertness, heart rate, and blood pressure. It also stimulates insulin release in the body, increasing fat storage.
