"Overweight people who snore, for example, may not even realize that their sleep is very disturbed.
They may think they get enough sleep and don't understand why they feel tired during the day.
The same applies to alcohol: It can help you get to sleep, but the normal pattern of sleep will be disturbed, and you may not get enough deep sleep.
So your time in bed may be okay, but sleep duration is not." - Simon Archer, Ph.D, head of the department of biochemical sciences at the University of Surrey