Can’t sleep? Many people solve this problem easily with a nightcap and many believe their sleep is better when they drink.
Sleep does come easy when you have a drink in the evening and you’ll sleep deeply in the first part of the night. Great, right? Science tells us that alcohol is actually not such a good solution – firstly because it reduces the REM stage and disrupts sleep in the second half of the night. Secondly, solving your sleep problems with alcohol night after night deletes the initial benefits and can easily lead to alcoholism.
Here we discuss how alcohol affects sleep according to recent research.
How alcohol makes you sleepy
Alcohol has a similar effect as sleep deprivation in that it increases the amount of a substance called adenosine in the brain.
We get adenosine as ATP (energy source of cells) breaks down and the longer we are awake, the more adenosine is in our brain. Alcohol doesn’t allow our nerve cells to take up some of the adenosine so it increases in amounts and builds up outside of cells. High adenosine means we feel tired and can’t think clearly.
When we sleep our brain cells shrink allowing the bodily fluids to “wash away” all the substances that have accumulated. This refreshes or “reboots” the brain and prepares it for the demands of the next day.
Resistance to sleep loss also means resistance to alcohol?
One study used the information from above to see how human cognition (thinking) was affected by sleep deprivation and alcohol separately.
They found some people are simply not impaired by alcohol as others. Scientists can’t tell why this is so. What they did notice was that the same group of people who were more resistant to alcohol were also resistant to sleep loss, that is, after sleeping for only five hours or less their vigilance was still good.
The other group consisted of people who are vulnerable to sleep loss and alcohol. In fact, even after given the chance to recover they didn’t recover fully, unlike the resilient group who was perfectly fine after getting one night of recovery sleep.
Does alcohol shorten your sleep?
Frequent drinking is related to short sleep, although it is not clear whether short sleep causes people to drink more (probably to cure insomnia) or maybe drinking leads to short sleep. Some authors warn that alcohol as a sleep aid can lead to alcoholism as tolerance increases.
A Canadian study from 2012 has shown a difference in sleep length when researchers compared heavy drinkers (having more than 14 drinks per week for men and more than 7 for women) and non-heavy drinkers who typically drink less than the amount above.
They were all categorized as short, average, and long sleepers where short sleep was considered 6 hours or less, average seven to eight hours, and long nine hours or more. Short sleepers were the most likely to binge drink, especially men – over 40% of them reported consuming five or more alcoholic drinks on one occasion.
This study included men and women with ages ranging from 18 to 64.
Alcohol and staying asleep
When non-alcoholics drink they fall asleep more easily and have more deep sleep (increased delta wave activity) than usual in the first half of the night.
This sounds like great news because nobody wants to stay up when they should be sleeping and deep sleep carries numerous benefits regarding health and mental wellbeing – immune and cardiovascular system, metabolism, memory consolidation, brain functions, hormones – they all get maintained and balanced during deep sleep.
However, in the second half of the night their sleep gets disrupted. There are more awakenings (that people are often unaware of) and there ́s much less REM sleep during the whole night. After a period of constant drinking before bed stops people tend to have a REM relapse, which means they will spend an increased amount of time in this stage of sleep in an attempt to recover the lost REM.
Another reason against alcohol is that the positive effects disappear by the 6th night of constant “nightcap”.
Alcoholics and sleep problems
Alcoholics typically have sleep problems at all times – in periods of drinking and in periods of abstinence. The most common disruptions and diseases include insomnia, excessive daytime sleepiness (EDS), sleep-related movement disorder, and abnormal sleep architecture (meaning their cycle differs from that of a healthy person). Circadian rhythm (the daily biorhythm of our body) can also be disrupted.
Sleep problems during alcohol withdrawal are likely to come as a result of the abovementioned disrupted sleep homeostasis.
Teens, sleep, and alcohol
As adolescents get older, they go through numerous developmental changes. They seek more independence and their circadian rhythm shifts to a later time. This means adolescents begin preferring later bedtimes and later wake times which does not match their school times.
Circadian disturbance and poor sleep are linked to a bad mood, depression, and altered reward function.
Some authors believe that adolescents are at a high risk of alcohol use disorder due to all the factors combined – later sleep time which is related to circadian dysregulation, which is then related to the altered reward system, and finally to alcohol consumption.
Alcohol has a more stimulating effect on adolescents, whereas it also has sedating properties for older people. This leads to an inability to fall asleep after alcohol consumption.
- Alcohol Dependence and Its Relationship With Insomnia and Other Sleep Disorders. https://onlinelibrary.wiley.com/doi/abs/10.1111/acer.13217
- Current Alcohol Use is Associated with Sleep Patterns in First-Year College Students. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863222/#
- Short sleep duration is associated with greater alcohol consumption in adults. https://www.ncbi.nlm.nih.gov/pubmed/22841812
- Alcohol and the sleeping brain. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5821259/