How does caffeine affect sleep?

Caffeine is one of the most commonly used stimulants in the world and is found in many beverages such as coffee, tea, and energy drinks. People often consume caffeinated drinks to stay alert and boost their concentration, but caffeine can also affect sleep. According to a study published in the Journal of Clinical Sleep Medicine, moderate consumption of caffeine can lead to a longer time to fall asleep and reduced sleep quality.

Caffeine interacts with the brain by speeding up the messages between the brain and body, which can make people feel more awake. This happens because caffeine binds to adenosine receptors in the brain, blocking them and thus inhibiting feelings of sleepiness. However, long-term caffeine use may lead to an increase in the production of adenosine receptors in the brain, which can reduce the effectiveness of caffeine over time.

Caffeine also triggers the release of stimulating neurotransmitters such as dopamine, which makes people feel satisfied and motivated, and adrenaline, which triggers feelings of exhilaration. However, caffeine can disrupt the natural sleep-wake cycle, as adenosine levels are typically higher at night, making people feel sleepy by bedtime. When caffeine inhibits adenosine, people may become too alert to fall asleep.

Caffeine also interferes with sleep-inducing hormones such as melatonin, the main metabolite of which is reduced after consuming caffeine. Caffeine stays in the body for several hours and can take about 6 hours for half of its effects to be eliminated, which is why it's suggested to not consume caffeine close to bedtime. Furthermore, caffeine reduces slow-wave sleep, which is the stage of deep, restful sleep that leaves people feeling refreshed and alert in the morning.

The effects of caffeine on sleep can vary from person to person based on factors such as age, metabolism, genetics, and tolerance. Older people tend to become more sensitive to the stimulant properties of caffeine, while genetic differences in the release of adenosine can lead to differences in caffeine sensitivity between people of the same age. Additionally, individuals who consume less caffeine are more sensitive to its side effects, while frequent coffee drinkers may not face the same challenges when falling asleep.

References:

Bond, L. (2023, February 2). How does caffeine affect sleep? Live Science. Retrieved February 3, 2023, from https://www.livescience.com/how-does-caffeine-affect-sleep