If you’ve ever been in Paris and ventured out onto the streets in the early morning, you will have probably observed a practice which, I believe, is unique to Paris. You will see water gushing out of outlets in the gutters and a small army of green-clad men armed with witchy-looking broomsticks sweeping the water along the street. There are 12,000 of these outlets—bouches de levage—in the streets of Paris and they help keep the streets clean and tidy.
Scientists have recently discovered that our brains have a similar system. It’s called the glymphatic system and it’s comprised of a series of tubes that carry fresh fluid into the brain, mix the fresh fluid with the waste-filled fluid that surrounds the brain cells, and then flush the mix out of the brain and into the blood. The process primarily occurs during deep sleep.
The system is thought to have two functions. The first is to flush out the waste that accumulates in the brain, such as metabolites and soluble proteins. Some of these, such as amyloid-b and tau, are neurotoxic, so eliminating them is very important. The second function is to distribute nutrients to the brain, a bit like the milkman used to do to our households first thing in the morning.
The discovery is very exciting because scientists think that these glymphatic processes may play a role in Alzheimer’s pathology. In short, interfering with the process may increase the risk of the disease.[i] If the scientists are right, then it suggests that there are some lifestyle choices we can make to reduce our risk of Alzheimer’s. Current thinking is that making sure you have Omega-3 in your diet, exercising regularly, intermittent fasting and sleeping on your side may all help.
The influence of alcohol on the process is interesting. There is some evidence that small amounts of alcohol may improve glymphatic function, but also that imbibing large amounts or chronic use of alcohol seriously disrupts it. There is also a secondary effect of alcohol via the HPA (hypothalamic-pituitary-adrenal) axis, where chronic alcohol use increases the production of cortisol and the stress response. A dysfunctional HPA axis and high levels of cortisol are associated with Alzheimer's.
Alzheimer’s Research UK estimate the number of people living with dementia to be close to one million in 2021 (944,000) and by 2050 this figure is expected to rise to 1.6 million, so any progress we can make in reducing these numbers is very important.
So there are very compelling reasons to make good quality sleep a priority and keeping alcohol consumption to a minimum, but there are also short-term impacts of alcohol on sleep that make a strong case for reducing alcohol intake.
A large study in Finland found that alcohol had a dose-dependent effect on the autonomic nervous system. Sleep quality was degraded by 9.3% after even a small amount of alcohol (less than 2 drinks for a man and less than 1 for a woman) and when a man consumed two drinks (or a woman one drink), sleep quality was degraded by 24%. More than this degraded sleep by 39.2%. [ii]
According to The Sleep Foundation, drinking alcohol before bed can increase the suppression of REM sleep. Since alcohol is a sedative, sleep onset is often shorter for drinkers and some fall into deep sleep rather quickly. As the night progresses, this can create an imbalance between slow-wave sleep and REM (Rapid Eye Movement) sleep, resulting in less of the latter and more of the former. This imbalance decreases overall sleep quality, which can result in shorter sleep duration and more sleep disruptions.[iii] REM sleep is important as this is when a lot of our memory consolidation takes place and it’s also thought to help us to regulate our emotions.[iv] When we are deprived of quality sleep, we are more likely to have negative emotional responses and our reactions to positive emotional events are subdued.
In lay terms that means we get crotchety and are less likely to have a healthy response when people are nice to us. Neither of those things are good.
Alcohol also often plays a role in insomnia. Regular drinkers can get into a vicious circle of having poor sleep so feeling very tired during the day and then drinking to help them fall asleep, which only has the effect of further degrading sleep quality.
The Sleep Foundation report that binge drinking—consuming an excessive amount of alcohol in a short period that results in a blood alcohol level of 0.08% or higher—can be particularly detrimental to sleep quality. In recent studies, people who took part in weekly were significantly more likely to have trouble falling and staying asleep. These findings were true for both men and women. Similar trends were observed in adolescents and young adults as well as middle-aged and older adults.
Alcohol also increases the incidence of sleep apnea (abnormal breathing and temporary loss of breath during sleep) by 25%.
I know from my own experience, and what our clients tell us, that getting a good night’s sleep is one of the greatest blessings of going alcohol-free. My experience was that I was chronically tired all the time, even when my alcohol intake was relatively modest. I used to drive a lot with my work, travelling to far-flung offices to do project work and staying alert while driving was a huge challenge. I used to end up drinking too much coffee and energy drinks which, of course, robbed me of sleep, thereby perpetuating my exhausted state.
Now I look forward to getting into bed and getting a great night’s sleep. I don’t always sleep right through the night—sometimes I am awake for a while in the middle of the night—but even my worst night’s sleep is better than my best night when I was drinking.
[i] The Sleeping Brain: Harnessing the Power of the Glymphatic System through Lifestyle Choices. Brain Science 2020 Nov; 10(11): 868.
[iv] Vandekerckhove, M and Yu-Lin Wang. Emotion, emotion regulation and sleep: An intimate relationship. AIMS Neurosci. 2018; 5(1): 1–17.
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