Caffeine and sleep: What’s the Relationship?

Caffeine and sleep

Do you drink coffee after dinner? Do you drink green tea before going to sleep? One study found that 90% of adults between 18 and 58 drink coffee in the afternoon (12:00 pm to 6:00 pm), while 68.5% consume caffeine in the evening (6:00 pm to 12:00 am). Unfortunately, caffeine can have a significant impact on the quality of your sleep.


Caffeine and Sleep: 

One study had participants take a 400 mg caffeine pill (about the equivalent of 32 ounces of coffee) either at bedtime, 3 hours before bedtime or 6 hours before bedtime. Each day, the participants actually took a pill at each time, however one of the pills was caffeine and the other two were placebos. On one day, all 3 pills were placebos. Researchers then tracked sleep via a wireless sleep monitor and self-reported sleep measures. The researchers found that caffeine reduced sleep time when taken at bedtime, 3 hours and even 6 hours. Caffeine actually reduced total sleep time by an average of 41 minutes when taken 6 hours before bedtime. Taking caffeine 6 hours before bedtime also more than doubled the amount of time it took to fall asleep, increased wake time during sleep by 8 minutes, and reduced stage 1, stage 2 and slow wave sleep!



Another study found that taking 200 mg of caffeine first thing in the morning (at 7:10 am) also impacted sleep later that night (although slightly). So if you’re having trouble sleeping, you might want to consider giving up caffeine altogether. If not, the earlier you drink caffeine the less it will impact your sleep. Don’t forget that caffeine isn’t just in coffee. Other common sources of caffeine include soda, tea, chocolate and energy drinks.



Drake, Christopher, et al. “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 (2013): 1195.

Landolt, Hans-Peter, et al. “Caffeine intake (200 mg) in the morning affects human sleep and EEG power spectra at night.” Brain research 675.1 (1995): 67-74.

Penolazzi, Barbara, et al. “Individual differences affecting caffeine intake. Analysis of consumption behaviours for different times of day and ventolin.” Appetite 58.3 (2012): 971-977.