That extra afternoon jolt of caffeine may be responsible for your tossing and turning at night. New research looked at caffeine’s effects on sleep taken 0, 3, or 6 hours before going to bed.
The study published in the Journal of Clinical Sleep Medicine involved 12 healthy normal sleepers. Researchers at Henry Ford Hospital and Wayne State University in Detroit looked at the effects of a given dose of caffeine taken at different times before 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 by more than one hour. However, subjective reports suggest that participants were unaware of this sleep disturbance.
“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. He is an investigator at the Henry Ford Sleep Disorders and Research Center and associate professor of psychiatry and behavioral neurosciences at Wayne State University in Detroit. “People tend to be less likely to detect the disruptive effects of caffeine on sleep when taken in the afternoon,” noted Drake. He also is on the board of directors of the Sleep Research Society.
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.