The power of sleep to protect immunity
Sleep

The power of sleep to protect immunity

Like most of us, you probably feel and look your best after a great night’s sleep. But it seems that sleep has a major role to play in keeping us healthy by fighting off viral and bacterial infections. A number of studies have shown that sleep can help you fight off an infection, while sleep-disrupting conditions like chronic stress can make you susceptible to getting sick.

Because sleep is the time when your body is doing its important healing and repair work, sleep also influences how fast you recover if you do get sick. According to a study published in the journal SLEEP, ongoing insomnia may even reduce your ability to respond to the flu vaccine.

How sleep affects immunity

Scientific research has shown that sleep deprivation can affect your immune system, and that people who aren’t sleeping well, or for long enough are more likely to get sick after becoming exposed to a virus.

Sleep improves the potential ability of some of the body's immune cells to attach to their targets. Researchers in Germany, led by Stoyan Dimitrov and Luciana Besedovsky, explains how sleep can help the body fight off an infection, by helping certain immune cells (T cells) attach to their targets more efficiently. T cells fight pathogens within the cells, such as the common cold, flu, and even cancer cells.

When T cells identify a virally infected cell, they activate a sticky protein called integrins, that lets them attach to and kill infected cells. By comparing T cells from healthy volunteers – who either stayed awake or slept all night – the researchers found higher levels of integrin activation in the sleeping volunteers.

If sleep is disrupted, the stress hormones adrenaline and noradrenaline, and pro-inflammatory molecules called prostaglandins can prevent healthy T cells from functioning, and make integrins less ‘sticky’. Stress hormone and prostaglandin levels drop during sleep, enabling T cells to stick to and kill virus-infected cells.

During sleep, your immune system also makes and releases cytokines – a type of protein that targets infection and inflammation – helping it respond to pathogens such as viruses. So if you’re not getting plenty of sleep, your body may not have enough of these protective cytokines to help you resist infection.

How much sleep does your immune system need to resist infection?

The optimum amount of sleep for most adults is 7-8 hours of good sleep each night. Children need around 10 hours of sleep or more, while teens need 9-10. For adults, sleeping more than nine hours may cause difficulty falling or staying asleep. In all cases, consistency is essential. We realise this is easier said than done, but setting the intention to support healthy sleep is absolutely worth the effort for your mental and physical health. 

Naps fill the gaps

If you can’t always get seven to eight hours of sleep a night, taking regular siestas can help. Grabbing two naps of 30 minutes each in the morning and afternoon, is shown to lower stress and offset the immune-suppressing effects of sleep deprivation. If taking an extra hour out of your busy day sounds impossible, try 20 minutes during your lunch break, and work from there. An ergonomic, easily portable pillow can help you benefit from a little extra rest wherever and whenever you can get it. 

So it seems that sleep (along with laughter of course) really is the best medicine for staying healthy in the long-term. As well as supporting the immune system to fight infection, sleep helps us reduce the risks of cardiovascular disease, obesity and diabetes, in addition to slowing damage to the brain caused by Alzheimer’s. 

Of course, there’s more to preventing illness than staying well rested. It’s also essential to practice strategies to stay well such as washing your hands thoroughly with soap, avoiding people who are under the weather, and coughing or sneezing into the elbow or a tissue. But sleep is still key to support overall wellbeing. That way, if you do come down with a virus or bacterial infection, you’ll be able to bounce back faster, and get on with your life. 

Further reading

Behaviourally assessed sleep and susceptibility to the common cold

Sleep, Don't Sneeze: Longer Sleep Reduces the Risk of Catching a Cold

Sleep Duration Linked to Vaccine Response

How Sleep Strengthens the Immune System