Late Afternoon, Early Evening Caffeine Can Disrupt Sleep at Night

What You Need to Know: Caffeine consumption even six hours before bedtime can have significant, disruptive effects on sleep.

Background: Sleep specialists have long suspected that caffeine can disrupt sleep long after it is consumed.

The Study: 400 mg of caffeine (about 2-3 cups of coffee) taken at bedtime, three and even six hours prior to bedtime significantly disrupts sleep.

 “People tend to be less likely to detect the disruptive effects of caffeine on sleep when taken in the afternoon,” noted Drake, who also is on the board of directors of the Sleep Research Society.

Drake and his research team studied 12 healthy normal sleepers, as determined by a physical examination and clinical interview. Participants were instructed to maintain their normal sleep schedules. They were given three pills a day for four days, taking one pill at six, three and zero hours prior to scheduled bedtime. One of the pills contained 400 mg of caffeine, and the other two were a placebo. On one of the four days, all three pills were a placebo. Sleep disturbance was measured subjectively with a standard sleep diary and objectively using an in-home sleep monitor.

Results: Even when caffeine was consumed six hours before going to bed, objectively measured total sleep time was dramatically reduced (more than one hour). Participants were unaware of this sleep disturbance.

My Take: This is the first study to investigate the effects of a given dose of caffeine taken at different times before sleep. The results suggest that caffeine generally should be avoided after 5 p.m. in order to allow healthy sleep. I’m Dr. Michael Hunter, and as a Seattle resident, greatly enjoy a good cup of coffee (only not within six hours of bedtime!).

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

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Journal References:

  • Christopher Drake, Timothy Roehrs, John Shambroom, Thomas Roth. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine, 2013; DOI: 10.5664/jcsm.3170
  • American Academy of Sleep Medicine. “Late afternoon, early evening caffeine can disrupt sleep at night.” ScienceDaily. ScienceDaily, 14 November 2013. <www.sciencedaily.com/releases/2013/11/131114155838.htm>.

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