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“A good laugh and a long sleep are the best cures in the doctor’s book,” according to an old Irish proverb. Given the current COVID-19 pandemic, there may not seem like there’s much to laugh about at the moment. But neuroscientists are learning that getting a good night’s rest can be one of the best things you can do to keep your immune system – as well as your general mental health and well-being – in tip, top shape.
Robert W. Greene, M.D., Ph.D., the Sherry Gold Knopf Crasilneck Distinguished Chair in Psychiatry at the University of Texas Southwestern Medical Center and member of the Dana Alliance for Brain Initiatives (DABI), has spent his career studying how the mammalian nervous system changes between sleep and wake states – including how such changes may impact immune function. Here, he explains how sleep affects the immune system, that sleep disruption is linked to almost every psychiatric disorder, and it’s important to get your Z’s even during periods of heightened stress.
Why think there might be a connection between sleep and immune function?
In recent years, there’s been an explosion in our understanding of both the immune system as well as what happens in the body and brain during sleep. A lot of that information comes from looking at what happens when there is a lack of sleep or when a person’s sleep needs are increased for some reason. We’re only now just beginning to effectively integrate that knowledge in a way that we can look at the interaction between sleep and the immune system.
What is a lack of sleep doing to our immune system?
Depriving a person or animal of sleep has been one of our best ways of understanding sleep’s function – what sleep is actually for. Sleep deprivation is something many of us do to ourselves all the time. We know that when we don’t sleep well, we don’t function as well. But a lack of sleep can also affect how well we can fight off an infection.
In experiments where we study sleep-deprived animals, we can look at what kind of response animals, including humans, have to different stimuli as compared to those that are getting adequate sleep. That has taught us a lot about what sleep may be doing. In general, sleep is a time when cells can perform their normal housekeeping kind of tasks. They are undisturbed by the demands of running around to look for food or avoiding dangers so they can do basic clean-up and other things to keep themselves healthy and functioning properly. In a sense, one can think of sleep as being a time when cells, especially brain cells, can live for themselves. The same thing can probably be said for the immune system, which tightly interacts with the nervous system.
If you have ever been sleep-deprived, you’ve probably experienced a feeling of general malaise. When you prevent sleep from occurring, it isn’t that these housekeeping tasks aren’t happening. But they are happening to a lesser extent. So, your nervous system and your immune system just don’t work as well overall.
How can sleep help bolster the immune system?
We now understand that the immune system responds to sleep loss, especially chronic sleep loss, with a general pro-inflammatory state. It’s very low-grade but it can become a chronic state over time. This can predispose you to infections – make you a little more susceptible to pathogens than you normally would be. You increase your risk of bad effects when you are exposed to bad infectious agents. Your body just isn’t as equipped to fight them off in part, because the immune system has not been primed and ready to go by a good night’s sleep.
It is also important to mention that sleep plays a vital role in consolidating memories. Similarly, this can include immunological memories. Vaccines rely on those immunological memories to work properly. Vaccinations work because they help your body build an antibody response. That way, if you ever come across what you’re being vaccinated against, the body remembers and can respond with the most effective immune response to that specific pathogen. That kind of long-term memory appears to be greatly enhanced by sleep – and can be suppressed by loss of sleep. You need that long-term memory installed after a vaccination to help it work its best. We don’t yet have a vaccine for COVID-19, but we do have vaccines for influenza and pneumonia. You don’t want to catch any of those things – and having one of them can make you more susceptible to picking up another type of infection. So, when a vaccine does become available, or if you get one of these existing vaccines, you want to make sure that you get a good night’s sleep afterwards. It helps the vaccines work better.
I would also mention there may be good reason that we tend to be more tired and sleep more when we do have an infection. We haven’t worked out all the mechanisms of why that is at this point, but that sleep is likely part of the body’s defense system to help you get well. It’s probably a way of allowing the body to maintain its strength as much as it’s able to in the face of this sort of infectious challenge.
How does poor sleep affect mental health and well-being?
There is not a single major mental illness that doesn’t include sleep disruption as one of the major symptoms. When there is sleep loss, a metabolically-driven homeostatic sleep circuit in the brain, which acts to promote protein and energy metabolism and rebalance synaptic activity, does not work as well. There is a massive change in gene expression that includes a significant enrichment of risk genes for psychiatric disorders, including autism, schizophrenia, and neurodegenerative disorders like Alzheimer’s disease. Further, chronic sleep loss, promotes that chronic inflammatory state in the brain, as well as a metabolic state associated with pre-diabetes. These latter two characteristics may account for some of the mood disorders, like depression and anxiety, that are associated with chronic sleep loss.
Public health experts have been recommending that people wash our hands and adopt social distancing protocols. Should they also be telling us to get a good night’s sleep to prevent COVID-19 infection?
Overall, yes. Though I would caution how much sleep equates to a good night’s rest – 7 hours or 8 hours or a different amount – really does seem to vary from person to person. That said, if you want to reduce your risk of being infected, with everything else being equal, then you want to get a full night’s sleep and set your immune system up to work its best.
What are the best ways to do that?
Sleep hygiene is important. Prepare yourself for sleep before you go to bed. It helps to have a relaxing routine. Don’t do anything that’s going to rile you up or get you excited. For example, maybe stop watching the news a couple of hours before bedtime – not after you’ve already hopped into bed. Daily exercise can help you get a good night’s rest. Too much caffeine or alcohol can disrupt sleep. Go to bed at the same time every night and try to get up at the same time every morning. With so many work and school closures, you may be tempted to stay up late or sleep in. But maintaining an effective sleep schedule is one of the best ways to make sure you get the sleep you need to keep your immune system working its best.
I don’t think most people realize that there is this strong interaction between sleep and the immune system. Your immune system is your best defense against catching a disease. So, if you want your immune system to work optimally, you need to sleep optimally.