If you have a nightcap before bed, to help you sleep, it could be doing you more harm than good!

Disrupted sleep

For those who drink a nightcap before sleeping, the alcohol initially acts as a sedative but may disrupt sleep later on.

What happens when you drink alcohol before bed?

A study of the effects of alcohol on sleep electroencephalogram (EEG) power spectra in college students has found that pre-sleep drinking not only causes an initial increase in slow wave sleep (SWS) related delta power but also causes an increase in frontal alpha power, which is thought to reflect disturbed sleep.

“The take-home message here is that alcohol is not actually a particularly good sleep aid, even though it may seem like it helps you get to sleep quicker.”

Christian L. Nicholas, from the National Health and Medical Research Council and Peter Doherty Research Fellow in the Sleep Research Laboratory at The University of Melbourne, and his colleagues recruited 24 participants (12 female, 12 male) – all healthy 18- to 21-year-old social drinkers, who had consumed less than seven standard drinks per week during the previous 30 days. Each participant underwent two conditions: pre-sleep alcohol, as well as a placebo, followed by standard polysomnography with comprehensive EEG recordings.

A bad sleep aid

Results showed that alcohol increased SWS delta power during non-rapid eye movement (NREM) sleep, but there was a simultaneous increase in frontal alpha power. Nicholas explained that the increase in frontal alpha power that occurs as a result of pre-sleep drinking is likely to reflect a disruption of the normal properties of NREM slow wave sleep.