New research suggests poor sleep may limit the amount of protection individuals gain from the hepatitis B vaccine. However, we are still not sure the link is genuine and more studies are needed to find out whether sleep impacts on immunity.
BMJ Group News
What do we know already?
Past studies have linked missing sleep to hormone, blood sugar, and blood pressure problems in the short term. Long-term sleep problems have been linked to weight gain, diabetes, and even a shorter length of life.
There is some experimental laboratory evidence to suggest that poor sleep may interfere with the immune system - the body's natural defence against infections. But we don't know if that's the case in real life.
The current study set out to look at the impact of sleep on immunity in people going about their normal daily lives. American researchers in Pennsylvania followed 70 women and 55 men aged between 40 and 60 as they received the standard three doses of hepatitis B vaccine. Antibody levels were measured prior to the second and third vaccine injection and six months after the final vaccination to determine if the study participants had a good response to the immunisation.
The individuals were asked to keep a sleep diary and 88 of them also wore electronic sleep monitors, known as actigraphs, to obtain an objective measure of sleep on the three nights before and three nights after the first vaccine dose.
People who slept fewer than six hours on average per night were far less likely to respond fully to the hepatitis B vaccine as people who slept more than seven hours on average.
Specifically, shorter sleep duration (less than six hours a night, as measured by the actigraph and self-reported) was linked with a lower antibody response after the second dose of vaccine and a decreased likelihood of being clinically protected from hepatitis B by the end of the full vaccine course. These findings were independent of the person's age, sex, and their weight relative to their height - a measure of obesity known as body mass index.
Of the 125 participants, 18 did not receive adequate protection from the vaccine. Sleep quality (how well the person felt they had slept) did not appear to affect vaccination response.
How reliable is the research?
The study found a link, but it's important to remember that this is not proof that less sleep has a negative impact on the immune system, or that less sleep affects how well the body responds to the hepatitis B vaccine.
It is still unclear how important sleep is for the immune system.
The researchers did take into account factors that could have influenced the findings, for example, a person's sex or if they are overweight. They also asked the individuals to document in their diaries whether they were experiencing any psychological stress. Previous research has linked stress with altered vaccine responses.
We can't rule out that other things may also have influenced the results.
What does this mean for me?
There is still not enough evidence to say whether or not too little sleep can make vaccines less effective or interferes with the immune system.
We are only beginning to understand the effect sleep has on the way our bodies work.
Some people need more sleep than others but, on average, we need between six to nine hours of sleep per night in order to wake up feeling refreshed.
There is mounting evidence that lack of sleep, especially on a regular basis, is linked to health problems.
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