Restful sleep builds immunity
Immunization works better after adequate sleep
Conventional wisdom holds that a good night’s sleep reduces the risk of getting the flu. Researchers at the University of Chicago conducted an experiment to test this idea. Researchers recruited 25 healthy men with a mean age of 23 years. Eleven of the subjects had their sleep restricted to four hours (1-5 am) for six consecutive nights, followed by seven consecutive nights of 12-hour sleep recovery. After the sixth sleep-deprived night and before the beginning of the sleep recovery, subjects in the sleep deprivation group received an immunization for influenza. Fourteen men in control group slept their normal number of hours during the experiment and received their immunization on the same day as the sleep-deprived men. The influenza antibody titer (concentration) from day 0 to day 10 increased significantly more in the non-sleep deprived compared to the sleep-deprived men. After 3-4 weeks, the antibody concentrations were not significantly different between the groups. Thus, sleep deprivation shortly before or after immunization might compromise your immune system over the short run and increase risk of infection.
Subsequent laboratory studies showed that poor sleep led to reduced production of antibodies to hepatitis A and B and influenza. Susceptibility to infectious diseases also increased. But would these results occur in naturalistic settings such as at home? Researchers in San Francisco recruited 125 relatively healthy community-living adults with an average age of 50 years for a test. Participants received the standard 3-dose hepatitis B vaccination at time 0, 1 month, and 6 months. For three days on either side of each vaccination, participants wore an actigraph device that objectively measured sleep. Researchers measured antibody levels in blood samples collected at the time of immunizations 2 and 3. Data combined from the two immunizations showed that antibody levels were 26 percent lower for participants who slept fewer than 6 hours per night compared to participants who sleep more than 7 hours per night. In addition, participants who slept fewer than 6 hours per night had a 24 percent lower likelihood of being clinically protected from hepatitis B for compared to participants who slept more than 7 hours per night. If you plan to receive an immunization, make sure you get plenty of sleep before and afterwards.
Both sleep and circadian (daily) rhythms strongly affect immune system function. A recent review concluded that adequate, regular, restful sleep helps establish immunological memory. That is, your body has greater ability to respond faster to pathogens because your immune system is primed to defend against attack by specific pathogens. Studies of vaccinations show that a single night of normal sleep following vaccination promotes immune response to the vaccination. The positive effects are present a year later. During sleep, the body mobilizes its immune system utilizing pro-inflammatory signals. Even a single night of poor sleep creates stress on the body. Prolonged poor sleep leads to increased markers of inflammatory activity. Chronic, low-level inflammation is associated with chronic diseases including type 2 diabetes and cardiovascular disease. Other vaccination studies show that the immunological response declines after six days of restricted sleep.
A recent review strongly suggests that sleep disturbances powerfully influence the risk of infectious disease, the incidence and progression of several chronic diseases, including cardiovascular disease and cancer, and the onset of depression. The immune system has two aspects—adaptive and innate. Adaptive immunity refers to the proliferation of specific types of white blood cells that respond to microbial pathogens based on previous attack by the same pathogens. Innate immunity refers to various types of cells that respond to injury and pathogen presence with inflammatory responses. Sleep affects the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system, which regulate both types of immunity. Some aspects of immunity are influenced by circadian biorhythms while other aspects are influenced by sleep. Sleep loss, either experimentally induced or arising at home, impairs adaptive immunity, including responses to vaccines, and predicts inflammation. If you Sleep More & Better, you may reduce inflammation, improve your immune system, and reduce the risk of infectious disease.