SLEEPING more than seven hours a night may help the body mount a better immune response to vaccines, according to new research. Based on several studies, the findings of this meta-analysis suggest that getting less than six hours' sleep could result in a diminished antibody response.

Is it possible to boost the effectiveness of a vaccine by changing some of our behaviors or habits?

That's the question posed by a team of researchers from the University of Chicago and the French National Institute of Health and Medical Research (Inserm).

Previous studies have shown that the immune response to a vaccine can depend on several factors, including gender, age, weight or smoking.

Now, researchers are adding sleep to this non-exhaustive list.

The researchers found that people who slept less than six hours per night in the days surrounding vaccination had a blunted antibody response to the vaccine.

Conversely, people who got enough sleep (seven to nine hours per night) had a better immune response, benefiting more from the effectiveness of a vaccine.

"Insufficient sleep is a behavioral factor that can be corrected before vaccination and may not only strengthen, but also extend, the vaccine response," said the senior author of the research, Eve Van Cauter, professor emeritus of medicine at UChicago, quoted in a news release.

The findings, published in the journal Current Biology, were based on a meta-analysis of previous studies on the subject.

The American and French researchers also compared antibody responses according to the age and sex of the vaccinated individuals.

They found that the association between insufficient sleep and decreased immune response was strong for men, but that it was "not statistically significant" for women.

The researchers suggest that this difference was likely due to the fact that "none of the studies in women accounted for variations in sex hormone levels by menstrual cycle, use of contraceptives and menopausal status," their news release explains.

Moreover, the immunological impact of inadequate sleep was found to be greater in adults aged 18 to 60 than in those over 65.

The study explains that older people tend to get less sleep in general, which does not affect their routine.

The researchers hope that their study will serve as a basis for further research on the phenomenon, with the aim of providing greater clarity on its effects on both men and women.

"We need much larger studies that control for the sex hormone environment in women in particular," said Karine Spiegel, PhD, first author on the study and a research scientist at Inserm.

"We also need a better definition of how many days of short sleep duration affect the antibody response, and whether it is just before the vaccine, or also during and after.

Large scale studies that consider behavioral, demographic and hormonal characteristics should provide new insights that will translate to measurable impacts on vaccine efficacy."