Consider the 2015 study that measured the sleep of 164 healthy volunteers for a week. Participants were then administered nasal drops containing a rhinovirus (also known as the common cold) and monitored for another week. The study found that those who had slept five hours or less the week before were at four times greater risk of developing a cold compared to those who slept seven or more hours.
Behind the scenes
During sleep, your body produces and releases infection-fighting hormones and proteins that create an immune response to target infection. With reduced sleep, you produce fewer of these proteins, hindering your body’s ability to fight off viruses. Poor sleep also increases stress hormones, reducing the ability of your white blood cells — another part of your immune system arsenal — to fight off illness.
While sleep alone can’t guarantee that you won’t get sick, it can decrease the likelihood. And when you do get sick, you tend to feel tired and have an urge to sleep. Give in to that need because sleep can help lessen your symptoms and recovery time.
Sleep and immunity are linked not only when battling short-term infectious illnesses but also with wound healing and long-term, chronic disease. When you’re injured, for example, the immune system triggers a response such as redness, inflammation (swelling) or pain to help the healing process.
During healthy sleep, inflammation occurs during the night as part of the body’s self-regulating activity, which then returns to a normal level when you awaken. When you’re sleep-deprived, your body retains a low level of inflammation, which can then work against you by contributing to a range of issues from diabetes, cardiovascular disease and pain to neurodegenerative diseases like Alzheimer’s disease.
Another way poor sleep interferes with our immune system? Vaccine effectiveness. A landmark study tested subjects getting a flu shot to see if restricting sleep had any effect. One set of subjects slept four hours a night for six nights prior to the shot, while the others slept normally. The sleep-restricted were also allowed extended sleep after the shot — 12 hours per night for a week — to see if sleep loss recovery had an effect on vaccine success. Ten days post-vaccination, the sleep-deprived had fewer antibodies to the virus, in essence making the vaccine less effective even after the prolonged recovery period.
Be sure to prioritize sleep in your schedule to keep your immune system functioning optimally. And if you know you’ll be getting the flu vaccine — or any other type of vaccine — plan ahead so you can get adequate rest — seven to nine hours a night — the week before.
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