A recent study finds evidence that the ‘right’ amount of sleep could contribute to boosting our immune system and fighting the body’s susceptibility to infections, including cold and flu.

Researchers at the University of Bergen found that those who slept less than six hours and more than nine hours presented with a higher risk of infection than those who slept an average of seven to eight hours. Likewise, those suffering from chronic insomnia disorder and those with chronic sleep problems raised their risk for infection and the use of antibiotics. 

Prior studies suggest that sleep disturbances and the lack of adequate sleep raise the risk of infection.

“We wanted to assess this association among patients in primary care, where we know that the prevalence of sleep problems is much higher than in the population at large,” said Dr. Ingeborg Forthun, corresponding author of the study.

For the study, the scientists gave out questionnaires to 114 medical students at the University of Bergen to distribute to random patients recruited in the waiting rooms of the general practitioners.

In total, they gathered responses from over 1,848 patients across Norway, who had an average age of 52 years. Patients were asked questions concerning how long they slept, if they were early birds or night owls, or if/how long they have had trouble sleeping

Plus, they were asked the number of times they had had any sort of infection or taken antibiotics during the last three months.

The team also measured chronic insomnia disorder among all participants using a standardized scale.

From the survey, about 21 percent of respondents reported sleeping less than six hours, and only two percent reported sleeping more than nine hours. 16 percent of the patients also reported having taken antibiotics at least once during the previous three months.

Researchers found that those who reported sleeping less than 6 hours had a 27 percent higher risk of infection than those who slept an average of 7–8 hours. Meanwhile, those who slept for 9 hours or more had an even higher risk of infection—up to 44 percent. 

They also found that participants suffering from chronic sleep problems were more likely to report an infection and use antibiotics to fight it.

One study observed that upon infecting healthy adult individuals with rhinoviruses, those getting too little sleep prior to being exposed to the virus were more likely to develop a cold.

Another study on a similar topic also found a higher risk of respiratory infections in short sleepers or those suffering from sleep problems.

Researchers explain that their findings may hold since poor sleep could weaken the body’s immune system, thereby reducing the body’s ability to fight infection. 

However, the researchers note that there may be a potential for bias in their findings. For example, there is a possibility of the patients being more or less likely to recall episodes of infection or their intake of antibiotics in the past months. On top of that, they also were unaware of the reasons behind the patients’ visits to their doctor and if they had an underlying health problem that may have influenced sleep problems or infection. 

But Forthun says that “we don’t think this can fully explain our results.”

Nevertheless, to lessen how often we use antibiotics and increase our body’s resistance to infections, getting up to 7–8 hours of sleep is a good place to start. 

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