Eight hours of sleep a night improves the learning ability of immune cells in humans, Report informs with reference to a study published by the Brain, Behavior, and Immunity journal.

Scientists found that sleep promotes the migration of immune cells T-lymphocytes to the lymph nodes. “Training” of T cells occurs in them, including after vaccination. This explains why sleep improved the immune response of vaccinated people in previous studies.

To find out, biologists assessed the concentrations of different T-cell subtypes in the blood of healthy men and women who slept eight hours a night or simply lay in bed. Participants were fitted with special catheters to collect blood while they slept.

Patients who were allowed to sleep had higher levels of growth hormone and the hormone prolactin, and also had better contact between T cells and the protein CCL19, which plays an important role in their migration to lymph nodes.

Scientists believe that growth hormone and prolactin could be considered as new adjuvants to stimulate immune responses after vaccination, especially in older people who have lower levels of these hormones.