Sleep and Immunity

If you feel like you get sick after not sleeping well, science has your back.

People who sleep properly get sick less often, with short sleepers being four times more likely to catch a cold. Studies also show that a lack of sleep affects the immune system and how fast you recover if you do get sick.

In short, specific immune processes - which are critical to maintaining immune balance - only take place while sleeping.

This article explores the bidirectional relationship between sleep and immunity, shedding light on why sleep is critical to immunity.

How sleep affects the immune system

When we sleep, specific components of the immune system power up, such as cytokine production (associated with inflammation) and antibody release, in other words, we fight disease and injury better.

We know that immune signalling molecules (such as the cytokine interleukin) and brain neurochemical systems (such as the serotonin system) are amplified during infection, and sleep is critical to regulating their release.

Another way sleep affects the immune system is by changing the gut microbiome composition. Studies show that the gut helps regulate innate and adaptive immunity, and sleep deprivation is detrimental to this process.

Can sleep deprivation make you sick?

The evidence is overwhelming that sleep deprivation makes you more susceptible to sickness and increases the risk of chronic health problems.

Studies show that insufficient sleep makes you more likely to catch a cold and upper respiratory tract infections. Additionally, a lack of sleep makes the common cold and flu last longer due to lower immune responses.

Vaccine studies show that sleep is critical to immunisation, with people who don't sleep the night after receiving a vaccine having a weaker immune response.

Sleep is also linked to diabetes, heart problems, and stroke, with chronic sleep deprivation a common cause of severe health problems.

Over time, chronic sleep problems take a toll on your body, elevating your risk of disease and reducing your physical and mental performance. Unfortunately, your body can only do so much with insufficient sleep!

How many hours of sleep do I need to boost my immune system?

Healthy adults need between seven and nine hours of sleep each night to maintain a healthy immune system. However, if you have a cold, flu, or other illness, you need more rest to fight infection and get better.

Children need even more sleep – between nine and eleven hours, aged six to 13. Our guide to healthy sleep hours has more information.

I'm getting enough sleep, but I keep getting sick.

Sleep is one aspect of immunity – age, sex, infection history, genetics, diet, medication, and hygiene all play a role in immunity.

If you keep getting sick with colds and flu, something as simple as washing your hands more often and wearing a face mask in public spaces will help (the good news is you are probably used to this from the COVID-19 outbreak).

You should speak to your GP if you are concerned. Regular sickness – especially in winter – is not something to be worried about, but if sickness keeps you in bed, it is worth exploring the possibility of weakened immunity.

Weakened immunity is when your immune system can't fight infection. The flu, measles, and COVID-19 can weaken your immune system temporarily, making you susceptible to other illnesses after infection. Smoking, alcohol, and poor nutrition can also cause an imbalance in your immune system.

How can I sleep better?

We have ten tips for better sleep here, but there are three changes you can make to your lifestyle right now that could yield massive improvements:

• Avoid caffeine six hours before bedtime – caffeine stimulates you for six hours after consumption. Coffee, chocolate, and tea are no-nos.
• Turn off your smartphone an hour before bed – the blue light from your smartphone screen interrupts the release of the sleep hormone melatonin.
• Lift weights an hour before bed – this releases adenosine triphosphate (ATP), an energy-carrying molecule. As ATP depletes, it turns into adenosine, which causes drowsiness and can help you sleep.