Coffee taken at night will reset the body's internal clocks in charge of managing biological functions and genes according to daily cycles at night or during the day.
Research evidence suggests that the effects of caffeine are more than just making a person difficult to sleep. Quoted from the Independent page, the scientists reported, drinking coffee with the equivalent of double espresso, three hours before bedtime, can change the body clock back to an hour earlier.
Caffeine resets the body clock by delaying the increase in melatonin levels, the main hormone sleeping in the body. Melatonin levels that fluctuate help determine the body's natural time to sleep and wake up from sleep.
Two teams from the UK and the United States conducted research on a number of volunteers, and observed what happens to the cells of the affected individuals.
Lead researcher John O'Neill from the Medical Research Laboratory of Molecular Biology in London says the effects of caffeine on sleep make a person awake long known, but the fundamental impact on body clocks is unknown.