Good Night's Sleep May Benefit Immune System
By Amy Norton


NEW YORK (Reuters Health) - Conventional wisdom says getting enough sleep is key to staying healthy, and now there's new scientific evidence to back it up.

Researchers in Germany found that among a group of volunteers vaccinated against hepatitis A infection, those who got a good night's sleep afterward showed a stronger immune response to the vaccine.

This indicates a well-rested person's immune system may launch a stronger response to an invading virus than that of a sleep-deprived individual, according to the study's lead author.

The hepatitis A vaccine, like many other vaccines, exposes the immune system to an inactivated form of the virus. The point is to induce the body to produce antibodies against the virus so that if the real thing ever invades, the immune system is armed to fight it.

The antibody response to a vaccine provides a model for testing a person's immune response to infection.

In the new study, Dr. Jan Born and colleagues repeatedly measured levels of hepatitis A antibodies in the blood of 19 men and women until 28 days after vaccination. Half of the group got a full night's sleep after being immunized, while the rest were kept awake that night and the following day until evening.

Four weeks later, the well-rested group on average had nearly twice the antibody level, or titer, of the sleep-deprived group.

"Our results are amazing in that they show a decrease in antibody titer after only a single night of sleep deprivation," Born, a researcher at the University of Luebeck, told Reuters Health.

He added, however, that the sleepless group still had a strong enough antibody response to be effective.

The findings are published in the September/October issue of the journal Psychosomatic Medicine.

According to Born, one hypothesis is that hormonal changes during sleep may aid immune function. He noted that sleep boosts the release of prolactin and growth hormone, two hormones that lab experiments suggest enhance the immune response.

SOURCE: Psychosomatic Medicine Sept./Oct., 2003