Coffee habit at night disrupts sleep pattern, first human trial proves
Coffee habit at night can indeed disrupt a person's sleep pattern, the first human trial on caffeine's effect on the circadian rhythm has been proven.
People who drink double espresso a couple of hours before bedtime can experience a 40-minute delay in sleep because it can disrupt the body's internal clock. This was the result of the world's first human trial on caffeine's effect on sleep pattern, according to NDTV.
The study was conducted by the University of Colorado (CU) Boulder and the Medical Research Council's Laboratory of Molecular Biology in Cambridge. The researchers found out that caffeine intake in the evening delays the human circadian clock that dictates the body's sleep and waking up pattern, the report explains.
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"The study also showed for the first time how caffeine affects 'cellular timekeeping' in the human body," NDTV quotes CU-Boulder professor Kenneth Wright.
Algae, fruit flies, and other primitive species' circadian clocks have been known to be affected by caffeine. But the new test shows that even human circadian rhythms can also be influenced by caffeine, the report details.
The study involved three female and two male respondents who were put through a double-blind, placebo-controlled test for 49 days. They were tested under low light and a placebo pill, low light, and a 200-milligram caffeine pill, bright light and a placebo pill, and bright light and a caffeine pill. In all the conditions, the amount of the caffeine given was calculated according to the subject's weight, Latinos Health reports.
When biological nighttime approaches, the body increases the level of melatonin hormones and decreases when biological daytime begins in a 24-hour period, the report adds.
Wright said the subjects who took the caffeine pill under the low-light conditions exhibited a 40-minute delay in their sleep onset compared to the respondents who took the placebo pill under the same conditions. Bright light and a combination of bright light and caffeine can also delay the circadian clock by 85 minutes and 105 minutes, respectively, the results of the study showed.
Professor Wright said the study may provide an explanation to why individuals who drink caffeine a few hours before bedtime wake up later. It can also impact the treatment of some sleep pattern disorders. Moreover, it could help frequent travelers regulate the timing of their caffeine intake to shift their circadian rhythm to adapt to new time zones.
The study on coffee's effect on sleep pattern was published in the Science Translation Medicine journal on Sept. 16.
