How Alcohol Affects Sleep

A lot of people turn to alcohol to unwind at the end of a stressful day. A glass of wine, a finger or two of whisky, it all goes a long way to helping you relax. You may think it will help you to get to sleep.

There is some truth to this, of course. Alcohol does have some sedative properties. It will often help you to get to sleep more quickly.

However, the quality of sleep you will get will be greatly diminished by alcohol consumption. You will likely experience disruptions later in your sleep cycle, you will likely need to get up more to use the bathroom as your body processes the alcohol, and you will dehydrate more severely than is healthy.

Though you may have got to sleep more quickly, that glass before bed will cause you to be tired and groggy when you get up in the morning. Your body will not be replenished.

Alcohol and Sleep

Alcohol is a central nervous system depressant. It causes brain activity to slow down, hence its use as a sedative and relaxant. This means that it’s common to feel sleepy when drinking it.

image of good sleepMany of the aspects in the relationship between sleep and alcohol are relatively unknown. Causation is still in its early days in many cases. Correlations are easier to come by, however. Research has shown that those who drink large amounts of alcohol before bed will often be more prone to delayed sleep onset. They will also be more likely to suffer with disrupted sleep as their bodies process the alcohol throughout the night.

Alcohol consumption has therefore been convincingly linked to poor sleep quality, especially in excess. It is common for excess alcohol consumption to come hand in hand with various sleep disorders, most commonly insomnia or sleep apnea.

When you drink alcohol, it is absorbed into your bloodstream via your stomach and small intestine. Liver enzymes will metabolize the alcohol. However, this takes time – it’s a slow process, so there will be lots of excess alcohol continuing to circulate through your body.

As a good rule of thumb, therefore, it is a good idea to try not to drink alcohol less than four hours before going to bed, at least most of the time.

Though moderate drinking is considered safe in the long run, we all experience alcohol differently. Variables such as speed of consumption, age, gender, weight, body type and other lifestyle factors will give a high degree of individuality to alcohol experience. This includes how alcohol affects your sleep, though there are some common factors that will hit all of us to a greater or lesser degree.

The Sleep Cycle

The human body goes through various different stages during sleep – during the sleep cycle.

Normal sleep cycles are made up of four distinct stages. These are three non-rapid eye movement (NREM) stages and one rapid eye movement (REM) stage.

The first stage, an NREM, is the transition period between wakefulness and sleep. Here, your body will begin to close off. Your heart rate will drop, your muscles will relax, and your breathing and eye movements will begin to slow down. Brain activity will decrease, taking you into light sleep.

Then comes the second stage, another NREM, during which your heartbeat and breathing rates continue to slow down. Your body temperature will decrease, and your eyes will become still as you move towards deep sleep. Generally, this stage will be the longest in the cycle.

The third stage is the final NREM, during which your heart rate, breathing rate, and brain activity all reach their lowest levels. Eye movements will completely stop, and your muscles will totally relax. This is slow-wave sleep.

Then we have REM at stage four (and yes, that’s me in the spotlight…) This occurs about 90 minutes after you first fall asleep. Your eyes will begin to move again, and your breathing and heart rate will both speed up. It is thought that REM plays a significant role in memory consolidation – it is when most of your dreaming occurs as brain function increases.

How Does Alcohol Affect These Cycles?

Each full cycle should last between 90-120 minutes, giving each of us ideally four to five cycles each night (over roughly eight hours or so). NREM will be more dominant during the first couple of these cycles, with REM being a lot shorter. Then REM becomes more dominant in the latter cycles, lasting a lot longer (often 40 minutes plus). NREM will barely be present in these late cycles.

Drinking alcohol before sleep can further suppress REM during the first couple of cycles. In addition, alcohol can cause you to fall into a deep sleep faster, which will create a further imbalance between slow-wave sleep and REM sleep throughout the night. You will get far more NREM and far less REM sleep, giving you a poorer quality night’s sleep and less time in the critical memory consolidation part of your cycles.

Drinking alcohol will also often cause you to get up a few times during the night, as the alcohol is processed and expelled as urine – you will need to go to the bathroom more than you otherwise would. This further disrupts sleep, bringing you fully out of your sleep cycle.

Alcohol and Insomnia

Insomnia is a bit of a catch all term, defined as a persistent difficulty with sleep initiation, duration, consolidation, or quality. It is the most common sleep disorder and can lead to general fatigue and a broad range of physical and mental health concerns.

sleep after drinkingMany turn to alcohol to cure it, relying on alcohol’s nature as a sedative. Ironically, alcohol will only make the situation worse.

As we have seen, alcohol can reduce REM sleep and cause sleep disruptions. This means that you are more likely to wake up during the night, and for the sleep you do get to be far less restful than it could otherwise be. It can lead to insomnia due to this disruption and can exacerbate pre-existing insomniac tendencies.

Then, of course, people tend to self-medicate more, drinking more to get to sleep, thus making the situation worse. They may often tend to take in more caffeine and other stimulants during the day to give them energy, thus necessitating more sedation in the evening.

Binge drinking can have a particularly acute detrimental effect on your sleep quality. Binge drinking is excessive drinking during which your blood alcohol levels reach 0.08% or higher. Those who reach these levels on a weekly basis have been found to struggle significantly more to fall and stay asleep.

Chronic sleep problems have also been linked to long-term alcohol misuse. Our bodies are good at adapting – we build up tolerances to exogenous chemicals quite quickly. This includes alcohol. The more often we drink, the less effect alcohol has on us, the more we have to drink to feel it. This compounds the issues above, making them worse, leading many long-term alcohol users to develop insomnia symptoms.

Alcohol and Sleep Apnea

Sleep apnea is another common sleeping disorder. It is generally characterized by abnormal breathing and temporary loss of breath during sleep. There are two types of sleep apnea most commonly seen. Obstructive sleep apnea (OSA) will be caused by physical blockages in the back of the throat. Central sleep apnea (OSA) is caused by the brain being unable to properly signal the muscles that regulate breathing.

Sleep apnea-related breathing episodes can occur throughout the night. These breaks in breathing can cause disruptions to your sleep and can decrease overall sleep quality.

Sleep apnea can also be disruptive to those sleeping near you, as those with sleep apnea are also prone to loud snoring and intermittent choking sounds.

Alcohol is thought to exacerbate symptoms of sleep apnea as it causes the throat muscles to relax. This in turn creates more resistance during breathing, which can lead to heavier snoring and more disruptive breathing episodes. In addition, even small servings of alcohol before sleep can lead to OSA and heavy snoring, even in those with no history of sleep apnea.

Regular alcohol consumption can increase the risk of sleep apnea by up to 25%.

How Much is Too Much?

Even small amounts of alcohol can reduce sleep quality for many people, though the effects are highly individualistic. Nevertheless, it will be healthier in general to not drink before bed as often as possible (the odd weekend drink won’t be too damaging to most of us).

Small amounts of alcohol – no more than two servings per day for men or one serving per day for women – can decrease sleep quality by an average of 9.3%. Moderate amounts, meanwhile – which counts as two servings per day for men or one serving per day for women – raises this to 24%.

Naturally, excessive drinking – either by volume or frequency – will likely have a more negative impact on sleep and overall energy levels. High amounts of alcohol – above two servings per day for men or one serving per day for women – raises this even further, to 39.2%.

It is, therefore, a matter of degrees. Just be aware that any amount will bring about some kind of negative effect on your sleep quality.

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