Although you may feel drowsy after a drink, alcohol isn’t actually good for your sleeping patterns and in fact it can disrupt your deepest sleep, the kind needed for rejuvenation.
How Alcohol Disrupts Your Sleep
Sleep is made up of 5 phases, each needed for our brains to rejuvenate for the following day’s activity.
On a normal night, 25% of sleep involves rapid eye movement (REM) phase. When we drink alcohol, we enter deep sleep without the usual REM phase first.
According to Dr Tina Lam, research fellow at Curtin University’s National Drug Research Institute, you will feel like you’re sleeping more deeply and you will dream less.
“When you have alcohol in your bloodstream, it increases the slow-wave deep sleep and reduces the REM sleep,” Dr Lam explains.
Source: https://coach.nine.com.au/2018/06/15/10/55/alcohol-sleep
Dr Lam explains that as the night progresses the opposite happens.
As the alcohol leaves your bloodstream, your central nervous system switches to being dominated by glutamate. This is the brain’s excitement neurotransmitter and takes you into REM sleep, which is lighter.
“The drinker may experience less slow-wave/deep sleep, and get more REM sleep, which may result in more intense dreams or nightmares.
“This, along with the increased likelihood of snoring and tossing and turning, will result in sleep fragmentation and disruption. You’re more likely to get sweaty and have to get up to go to the bathroom too.”
Source: https://coach.nine.com.au/2018/06/15/10/55/alcohol-sleep
In other words, Dr Lam believes having a nightcap to help you sleep is counter-intuitive.You will have a lower quality of sleep and the length of your sleep will also be less.
Dr Lam also found that the more frequently alcohol was consumed, the less it will work in a sedative way.
“We get used to the sedative effects of alcohol very quickly,” Dr Lam explains.
“Within three to seven days of having a couple of glasses of wine after dinner to help us get sleepy [will see] the sedative effects diminish, but those counterproductive disrupting sleep effects continue.”
Source: https://coach.nine.com.au/2018/06/15/10/55/alcohol-sleep
Thus a poor sleep cycle is developed where you keep looking for alcohol to relax you and help you sleep, maybe even increasing the volume of alcohol you drink each time.
“People who drink the night before will have more disrupted sleep and feel less rested in the morning and will likely caffeinate up, which will still have residual effects at night,” Dr Lam explains.
“Then you might try to calm down again with a bit of alcohol, which will disrupt your sleep further. It’s quite easy to get into a vicious cycle.”
Source: https://coach.nine.com.au/2018/06/15/10/55/alcohol-sleep