You've probably noticed that you tend to get sick after a period of poor sleep. That's not a coincidence. Sleep and immunity are deeply connected, and skimping on sleep is one of the fastest ways to weaken your body's defenses against infection.
During sleep, your body produces and releases cytokines, proteins that help fight infection and inflammation. Some cytokines are produced primarily during sleep. Less sleep = fewer infection-fighting cytokines.
A study at the University of California, San Francisco exposed 164 healthy adults to the rhinovirus and tracked who got sick:
How you sleep before and after a vaccine affects how well it works. People who slept fewer than 6 hours after getting a flu vaccine produced less than 50% of the antibodies compared to those who slept 7+ hours.
Natural killer (NK) cells, which are your immune system's first line of defense against tumors, are significantly reduced after just one night of poor sleep. A single night of total sleep deprivation reduced NK cell activity by 70%.
Protect your immune system by sleeping on a consistent schedule. Use our free Sleep Calculator.
Consistently sleeping more than 9-10 hours has been associated with inflammation in some studies. But oversleeping is usually a symptom of an underlying condition, not the cause.
Yes, short naps can partially restore immune function after a poor night's sleep. But naps can't fully replace adequate nighttime sleep.
Being cold doesn't directly cause illness (viruses do). But being cold combined with being sleep-deprived weakens your immune defenses, making you more susceptible to viruses.