Wintering Well: Sleep for Immune Health

Alexandra Osellame - Bayleaf Clinical Nutritionist - BHSc(Nutritional and Dietetic Medicine)



Good sleep hygiene is important for regulating the circadian rhythm and in turn cortisol. Get to bed at the same time every night, wake up at the same time everyday and get your 7-8 hours. Keep screens out the bedroom, and no blue light two hours before bed.

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body’s defence system.


Scientific evidence is building that sleep has powerful effects on immune functioning. Studies show that sleep loss can affect different parts of the immune system, which can lead to the development of a wide variety of disorders.


For example, a modest amount of sleep loss (restricting the time allowed for sleep to 4 hours for one night) reduced natural killer (NK) cell activity to an average of 72%, compared with NK cell activity in participants who had a full night’s sleep. Research indicates that NK cells have a substantial role in killing tumor cells. Reduced functioning of NK cells was associated with a 1.6 times higher risk of dying with cancer (all sites) in an 11-year follow-up survey.


In a similar way, restricting sleep to 4 hours for one night led to the generation of inflammatory cytokines, which play an important role in the development of cardiovascular and metabolic disorders.


Sleep loss is also related to a higher risk for infection. Restricting sleep to 4 hours per night for 6 days, followed by sleep for 12 hours per night for 7 days, resulted in a greater than 50% decrease in production of antibodies to influenza vaccination, in comparison with subjects who had regular sleep hours.


Research shows that people who are sleep deprived, or consistently miss out on quality sleep, are not only more likely to get sick after being exposed to a virus, but their bodies will take longer to recover when they’re hit with an illness.


According to current estimates, two-thirds of all adults in developed nations are not getting enough sleep. One of the many consequences of losing out on sleep is a weakened immune system.


Individuals sleeping 6 hours or less a night were more than 4 times more likely to catch a cold compared to those who were logging 7+ hours of sleep.