Drinking even one strong coffee in the afternoon can knock an HOUR off your sleep
- The stimulating effects of caffeine last for up to six hours
- The findings suggest coffee should not be consumed after about 5 pmBe it frothy-topped, laced with alcohol or taken as a warming accompaniment to the cheeseboard, coffee is seen as the drink that makes a meal complete.But those late-night brews could be wiring you for a sleepless night ahead, research has shown.
According to scientists, drinking two or three cups of coffee, even six hours before bedtime, could cost you up to an hour’s sleep.
An after-dinner coffee can disrupt your sleep for most of the night, reducing the amount of shut-eye you get by up to an hour, according to new American research
Researchers from Wayne State University, Michigan, followed the sleeping habits of 12 people who were given pills containing 400mg of caffeine – the equivalent of two or three coffees.
Over four days, the trial members took their doses six and three hours before bedtime and another when they turned out the lights. One of the three daily pills was a placebo, with no caffeine in it, and on one day all three pills were placebos.
The results, published in the Journal of Clinical Sleep Medicine, revealed the pills made users toss and turn and lose up to an hour’s sleep – prompting a warning to avoid caffeine after 5 pm.
Psychiatrist Professor Christopher Drake, of Wayne State University, in Michigan, said: ‘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.
‘People tend to be less likely to detect the disruptive effects of caffeine on sleep when taken in the afternoon.
Sleep disturbance was measured subjectively with a standard sleep diary, and objectively using a home sleep monitor.
Dr Safwan Badr, of the American Academy of Sleep Medicine, said: ‘Sleep specialists have always suspected caffeine can disrupt sleep long after it is consumed.
‘This study provides objective evidence supporting the general recommendation avoiding caffeine in the late afternoon and at night is beneficial for sleep.’
The research published in the Journal of Clinical Sleep Medicine is the first to investigate the effects of a given dose of caffeine taken at different times before sleep.
The results suggest caffeine generally should be avoided after 5 pm in order to allow for healthy sleep.
Experts have found caffeine, the stimulant in coffee interrupts the flow of melatonin –the chemical that actually sends us to sleep.
Secreted by the pineal gland deep in the brain, the hormone helps control body rhythms and tells our bodies when to sleep and when to wake.
A previous study in Israel showed caffeinated coffee halves the body’s levels of the sleep hormone and leads to an hour and a half less sleep a night.
Britons spend about £850million a year on coffee. Researchers at Bristol University have shown drinking several cups each morning helps people to work more efficiently.
But heavy consumption of more than four cups a day has been linked to ill health.