The Impact of Alcohol on Your Sleep

20% of adults rely on alcohol to help them fall asleep. But even moderate drinking is more likely to interfere with your sleep than to assist it. 

 Alcohol can disrupt your circadian rhythms which can have quite an affect on your body’s systems. 

How does alcohol affect your circadian rhythms and what effect does this have on your health?

Your body’s 24-hour rhythms are governed by a master biological clock that coordinates the rhythm activity throughout the body. This rhythm regulates most of the body processes - metabolism, immune system, energy, sleep, sex drive, cognitive function and mood. 

Alcohol disrupts the circadian rhythm functioning by interfering with the master clock in the brain to synchronise itself. A disruption to this has a powerful influence on the way our body functions including the following: 

Liver function- the liver filters and helps the body metabolise food and chemicals (including alcohol) and pulls toxins from the bloodstream. The liver functions in accordance to the circadian rhythm and when alcohol is consumed and the circadian rhythm is affected this can cause compromised liver function. 

Leaky gut- the gut and it’s microbiome is often referred to as the body second brain, the circadian rhythm is vital for the health of the gut. The disruption that alcohol causes to the circadian rhythm can contribute to Leakey gut syndrome which weakens the lining of the intestinal tract making it more vulnerable to permeation - this then allows bacteria, toxins and food to leave the intestines and enter the bloodstream.  

Depression- people suffering from depression may already have disrupted circadian rhythms, then bringing alcohol into the picture, even in small amounts, may push the rhythms even more out of sync. 

Disrupted sleep and wake cycles- Alcohol surpasses melatonin which is key to help sleep and wake cycles. Research has shown that even just a small amount of alcohol, up to an hour before bed can reduce melatonin levels by 20%. 

Evidence also suggests that alcohol also interferes with the body’s other sleep-wake regulator: the internal sleep drive. Alcohol increases levels of adenosine, a chemical that regulates sleep by raising naturally in the body, the longer you have been awake. While also blocking other chemicals that stimulate wakefulness, this may make you sleep at times when you would naturally not sleep and therefore will throw your body’s natural sleep/wake cycle. 

 Studies have shown that the body metabolises alcohol differently at different times of the day. The most effective time of day for the body to metabolise alcohol is early to mid-evening hours - the traditional “happy hour”! However, in the morning body struggles to process alcohol more, so that Prosecco brunch may hit your circadian rhythm particularly hard!

 How alcohol affects sleep?

 The more you drink and the closer it is to bedtime, the more it will negatively affect your sleep- even moderate amounts. 

Alcohol alters the sleep pattern of your body, moving to lighter sleep as the night goes on, reducing sleep quality and leaving you more restless in the early hours, which will lead to more fatigue the next day. 

 Alcohol may reduce the time it takes for you to fall asleep- a sedative effect that you will build an intolerance to as you go and need more over time to have the same affect. The alcohol then goes onto affect the whole nights' sleep to come: in the early night when you are metabolising the alcohol, studies show more people spend more time in deep sleep and less time in REM which is very important for mental restoration, these changes can throw the body off completely. 

 During the latter part of the night after alcohol, sleep becomes more actively disrupted, which may see more active awakenings (which you may not remember).

People who go to bed with alcohol in their system may be more likely to wake up in the early morning and not fall back to sleep. 

How much alcohol is too much for sleep?

 Research shows the more you drink the increased impact on the circadian rhythm. But even a moderate amount of 2-3 drinks in the day is enough to impact sleep for most people. 

 Having a couple of drinks 2-3 times a week has not been shown to impact circadian rhythms, however, any more than that and you may notice a significant difference on your sleep quality if you reduce your alcohol intake. 

 Hope you find this useful and as always fire across any questions you may have,

Kasia :) 

BSc Sports Science, Women’s Fitness Specialist and Personal Trainer