A new study shows that caffeine consumption even six hours before bedtime can have significant, disruptive effects on sleep.
"Sleep specialists have always suspected that caffeine can disrupt sleep
long after it is consumed," said American Academy of Sleep Medicine
President M. Safwan Badr, MD. "This study provides objective evidence
supporting the general recommendation that avoiding caffeine in the late
afternoon and at night is beneficial for sleep."
Results show that 400 mg of caffeine (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). However, subjective reports suggest that
participants were unaware of this sleep disturbance.
The study is in the Journal of Clinical Sleep Medicine, which is published by the American Academy of Sleep Medicine.
"Drinking a big cup of coffee on the way home from work can lead to
negative effects on sleep just as if someone were to consume caffeine
closer to bedtime," said lead author Christopher Drake, PhD,
investigator at the Henry Ford Sleep Disorders and Research Center and
associate professor of psychiatry and behavioral neurosciences
at Wayne State University in Detroit, Mich. "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.
According to the authors, 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.
Reference:
http://www.medicalnewstoday.com/releases/268878.php
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