The worst time to consume caffeine in the day is six hours before bedtime as it can have significant, disruptive effects on sleep, a new study exploring sleep disorders has revealed.
The study led by Christopher Drake, PhD, investigator at the Henry Ford Sleep Disorders and Research Center, showed that about 2-3 cups of coffee taken at bedtime, three and even six hours prior to bedtime significantly disrupts sleep.
Even when caffeine was consumed six hours before going to bed, objectively measured total sleep time was dramatically reduced (more than one hour).
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.
The results suggest that caffeine generally should be avoided after 5 p.m. in order to allow healthy sleep.
The study was published in Journal of Clinical Sleep Medicine.