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The Relationship Between Caffeine and Sleep Quality

We all know that a cup of coffee can temporarily chase away the tiredness from a night without sleep. You feel energized and ready to focus on the day’s work at the moment, but what effect does caffeine have on your quality of sleep? According to different studies, caffeine can have drastically negative effects on sleep if consumed regularly, and some side effects on regular daytime functioning when consumed before bed.

​A group of people in the Detroit tri-county took part in a study where they were given 400mg of caffeine, and their sleep journals were recorded afterward. It was found that “caffeine reduced sleep by more than 1 hour” (Drake 2013), due to caffeine’s ability to enter the body’s central nervous system. What does this do to our sleep pattern? Well, when we are in deep sleep, or REM (rapid eye movement), our brain is producing important proteins, and our bodies stimulate the part of our brain that helps us to learn in our waking hours. When we consume caffeine, our REM cycle shifts to the part of sleep that is shorter. Therefore, our brain doesn’t get as much of a chance to carry out these functions.

If the participants were to consume caffeine regularly before going to bed, their ability to function during the daytime would worsen over time. Caffeine is a stimulant, meaning it will keep you awake longer, therefore shortening your time asleep, and making you feel tired the next day. Why exactly does this happen? Caffeine consumed during the day reduces our ability to absorb melatonin (a hormone that controls when you sleep and wake up). A large amount of caffeine can lead to sleep deprivation, which will cause decreases in brain functions, “lapses of attention, alertness, vigilance, and the speed of cognitive and psychomotor responses” (O'Callaghan 2018). These symptoms are usually not present when someone gets a full night’s rest. Also, many people have reported feeling jittery or anxious after consuming caffeine.

Some people do find a balance between caffeine and sleep by finding out their limits and sticking to them. However, this is found through a process of trial and error, which could lead to some of the symptoms listed above. The best way to avoid these caffeine-induced periods of sleep deprivation is to stay away from caffeine altogether.


1. Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 9(11), 1195–1200.

2. O'Callaghan, F., Muurlink, O., & Reid, N. (2018, December 7). Effects of caffeine on sleep quality and daytime functioning: RMHP. Risk Management and Healthcare Policy. Retrieved January 21, 2022, from



Author: Kayjah Taylor

Editor: Anum Khan

Health scientist: Ashlee Lee

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