While working remotely, most of us have had a greater nightly time frame in which to make an attempt at sleep; gone are commutes, late nights at the office, and after work drinks. And yet, according to a study conducted by King’s College London, nearly two-thirds of the public have reported a negative impact on their sleep since lockdown began. Maybe this shouldn’t surprise us -- the pandemic has caused a huge amount of financial and emotional stress, and we know stress often leads to a poor night’s sleep.
Stress aside, lack of daily structure (and therefore increased amount of time spent on screens) alone is enough to reduce quality and quantity of sleep. Have you found that your screen time has increased significantly during lockdown? If so, it’s likely affecting your sleep: light-emitting electronic devices used in the hour before bedtime have been proven to dramatically prevent the release of the sleep-inducing hormone, melatonin, by around 50%, resulting in a significant reduction of timing of REM sleep (the stage at which you are most likely to dream)
Increased screen time isn’t the only problem - increased alone time can also have an insidious effect on our sleep. Loneliness is on the rise: a study conducted by the Office for National Statistics (ONS) found that half of British 16-24 year olds reported feeling lonely during lockdown. This in itself is concerning as loneliness has been proven to lead to micro-awakenings (small moments of awakening that you don’t remember when you wake up) throughout the night.
"...it’s important that we think about what strengthens and weakens our immune systems. Sleep is a good place to start."
The generally accepted theory for this, as stated by John Hari in his book Lost Connections, is that our unconscious brain deems full sleep mode unsafe when experiencing loneliness because humans have evolved to operate in tribe-like settings, finding safety in numbers. Such micro-awakenings are dangerous; they have been proven to lead to low-grade inflammatory processes which can themselves lead to higher blood pressure and hypertension, concerningly both of which are Covid-19 risk-factors
Given that there is very limited research currently available on Covid-19 itself, when it comes to protecting ourselves from the virus, it’s important that we think about what strengthens and weakens our immune systems. Sleep is a good place to start.
Lack of good quality sleep can have an enormously detrimental effect on almost all our bodily systems, including our cognitive, metabolic and, most relevantly, the immune system. Research suggests sleep should be high up on our list of priorities during the pandemic. The fact that sleep is essential to immune function was highlighted in a 1983 study performed by the University of Chicago. In this somewhat disturbing experiment, rats were prevented from sleeping for multiple weeks. As time passed, the rats developed sores across their skin and suffered severe internal damage (including ulcers that had punctured their stomach lining); their immune systems had completely given up. Exhausted, the rats were no longer able to fend off even the most basic infection that normally would have caused no harm--the majority, in fact, died after 15 days without sleep.
"...staying up that extra hour to watch TikTok videos...may actually be leaving you susceptible to an infection you have not even been exposed to yet."
We sleep more when we’re sick; when under attack, the immune system stimulates the body’s sleep system, causing us to sleep for longer when fighting off an infection. But it’s not just sleep received during an infection that helps us combat sickness--the amount of sleep we get before coming into contact with an infectious element can determine our likelihood of falling sick altogether.
That direct relationship - between the amount of sleep received prior to exposure and likelihood of infection - was shown in a sleep experiment performed by Dr. Aric Prather of the University of California in San Francisco in 2015. Prather (using wristwatch devices) monitored the sleep of 150 healthy subjects for a week. The subjects were then quarantined and given a large dose of rhinovirus (or the common cold). In order to scientifically determine whether they had caught the cold or not, the subjects’ immune reactions were closely monitored via various bodily fluid samples which were tested for immune antibodies.
The results of this experiment were both significant and astounding: for subjects who had slept 5 hours on average the week prior to rhinovirus administration, the infection rate was 45.2%. Conversely, for subjects who had slept 7 hours or more the week prior, the infection rate was only 17.2%; even a couple of hours’ sleep makes an enormous difference to our susceptibility for infection. While you might think that the biggest detriment of staying up that extra hour to watch TikTok videos is feeling slightly groggy the next day, it may actually be leaving you susceptible to an infection you have not even been exposed to yet.
So what is it about sleep that helps fight infection? During sleep, there is a profound decrease in the activity of human stress systems, with significant drops in cortisol (the body’s main stress hormone), epinephrine, and norepinephrine (more commonly known as forms of adrenaline). Because these types of hormones tend to suppress immune function, our immune systems are stronger when we're asleep.
"...the WHO has now listed nighttime shift work as a carcinogen."
Conversely, substances that encourage cell growth and restoration such as the pituitary growth hormone and prolactin are steeply upregulated (increased in expression) during sleep. If we’re trying so hard to not be carriers, by taking precautions like wearing masks in public spaces, staying 2 metres apart, and not meeting up in big groups, do we not also have a responsibility to ensure our quality of sleep to avoid an infection in the first place?
There is more bad news for those of us that forego sleep in favour of a Netflix binge: lack of sleep significantly increases our chances of cancerous cells forming. In fact, the WHO has now listed nighttime shift work as a carcinogen (alongside the usual culprits such as smoking and processed meat). The research of neuroscientist Matthew Walker reveals this rather sobering statistic: on average, if sleep is restricted to 4 hours for one single night, there can be as much as a 70% drop in our Natural Killer Cell (NKC) activity the next day. NKCs work within your body to identify and destroy dangerous elements, including cancerous tumour mass. If these tumour-destroying cells (and thus our immune defences) are working at only 30% capacity, our risk of cancerous cells developing is vastly increased.
Sleep also affects immunity indirectly--it plays an important part in regulating appetite and is key to helping us make healthy food choices, instead of rash and impulsive ones. Good food adds fuel to our immune system, supplying it with necessary nutrients, and prevents any slowing down caused by poor-diet induced high blood pressure or increased fat levels. As the saying goes: you are what you eat.
During the Covid-19 era, it seems that bad sleep patterns are being forced upon us: we’re spending more time alone, working remotely on screens, and managing all sorts of stress caused by the pandemic. With that lack of sleep having such catastrophic effects on our immune system, we have to be mindful of the benefits of maintaining healthy sleep habits - if not for ourselves, then at the very least for those around us.