People who regularly get more than seven hours of sleep a night are more likely to respond to vaccination against hepatitis B compared to those who get in less than six hours, according to new research.

The differences were surprising, says researcher Aric Prather, PhD, a clinical health psychologist and Robert Wood Johnson Foundation Health & Society Scholar at the University of California, San Francisco, and the University of California, Berkeley.

"People who slept less than six hours on average were 11.5 times more likely to be unprotected [after the vaccine] than those who slept more than seven hours," he says.

He looked at the immune response to the hepatitis B vaccine in healthy adults.

Hepatitis B, a serious infection that affects the liver, is the cause of death each year for about 2,000 to 4,000 in the U.S., according to the CDC.

The study is published in Sleep.

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Sleep & Vaccines: Details

Prather assessed 125 men and women, aged 40 to 60, who got the vaccine.

He first tested them to be sure no one had been exposed to the hepatitis B virus.

The hepatitis B vaccine includes two doses given a month apart. Those are followed by another dose at six months.

The men and women wore a wrist device known as an actigraph to track sleep. Prather asked them to complete sleep diaries. He evaluated sleep duration, efficiency, and sleep quality.

"We measured antibody response just before the second vaccine and just before the third, and then six months after the series was over," he says.

By that time, a full response is expected.

About 15% of those vaccinated did not achieve full protection six months after the series ended, he found.

He looked at sleep habits and found a link. "What we found was, people who slept fewer hours on average produced fewer antibodies to the vaccine," Prather says.

Prather stresses that he found a link, not cause and effect.

However, he sees several ways in which sleep might affect antibody response. Sleep loss is linked to fluctuations in immune processes important to producing antibodies, for instance.

It's too soon and too simple, Prather says, to tell people to get a good night's sleep before a vaccination.

He found sleep habits over time, not just around the vaccine time, to be linked with a response.

More research is needed, he says.
Sleep & Vaccines: Perspective

The new findings, which looked at people's natural sleep habits, are strengthened by previous studies in the lab finding similar results when people's sleep was manipulated, says Firdaus Dhabhar, PhD, associate professor of psychiatry and behavioral sciences at Stanford University School of Medicine.

He reviewed the study findings.

"It is an important demonstration of how the duration of sleep in the participants' natural environment is related to the strength of their antibody response following vaccination, which is an index of how well protected they might be if actually exposed to the pathogen," he says.

The question of how much sleep a person needs is not simple, he says. "Different people are likely to need different amounts of sleep. A good indicator may be whether or not you generally feel rested when you wake up.''

"It is probably OK if you don't get enough sleep on occasion," he says. "But it's important not to let that become a regular state of affairs."

The new study ties in with previous research, says Kate Edwards, PhD, a lecturer in exercise physiology at the University of Sydney. "This adds to previous work, which found that disrupting sleep after a vaccination had negative effects on the immune response," she says.

In her own research, Edwards has found a single bout of exercise can help the immune response to a vaccination.

Prather's research looked at sleep habits over time, not just around the vaccination, Edwards says. Even so, she says, "we would still recommend a good night of sleep after getting a vaccine, and combining that with exercise at the time of getting the jab might give even better chances of a good response."