Study: Too Little or Too Much Sleep May Increase Your Chance of Infection

  • A new study has found that too little or too much sleep can increase an individual’s chances of infection.
  • While time spent asleep is important to fight infection, so is the quality of sleep a person gets regularly.
  • Experts recommend individuals focus on both proper sleep hygiene to optimize their sleep quality and sleep quantity.

A new study has found that too little—or too much—sleep per night could increase an individual’s chances of infection.

Your immune system is directly impacted by the amount of sleep you get each night, as well as the quality of that sleep. Sleep can actually either positively or negatively influence your risk of heart attack, obesity, diabetes, and cognitive function impairment.

But researchers are still collecting data on how sleep habits directly affect how different body systems function. According to Vijay Ramanan, MD, PhD, a neurologist at the Mayo Clinic in Rochester, Minnesota, sleep quality influences cytokines—types of proteins that have the power to stimulate or slow the immune system—which could explain how sleep may be tied to risk for infection. 

“It is still very possible that poor sleep really is fundamentally a proxy for other things that influence the risk of infection,” Dr. Ramanan told Health. “It may simply be that folks who get either too little or too much sleep are in poor health for other reasons, and may be at higher risk of infection.”

Still, he explained, “There are many good reasons to look at sleep as a modifiable factor that could improve one’s health overall and maybe even limit the risk of viral and other infections.”

Woman sleeping

Getty Images / Luis Alvarez

Sleep Quality Is Crucial

In the most recent study, Norwegian researchers recruited medical students to survey patients in general practitioners’ waiting rooms. The research team wanted to focus on people seeking primary care, as this population is known to have higher rates of sleep problems.

“We wanted to assess this association in a more real-life setting,” explained Ingeborg Forthun, PhD, a researcher at the Norwegian Institute of Public Health in Bergen, Norway, who co-authored the study.

In total, nearly 1,850 people were surveyed. The researchers found that patients with insomnia were 15% more likely to report an infection and nearly 50% more likely to have been prescribed an antibiotic. Those who slept less than 6 hours were nearly 30% more likely to report an infection and almost 60% more likely to have been prescribed an antibiotic in the last three months, compared to those who reported getting 7–8 hours of sleep, which the researchers noted to be the ideal amount for most adults.

Sleeping too much was found to also correlate with negative health effects. Those who reported sleeping more than 9 hours were 44% more likely to have had an infection compared to those who got 7–8 hours.

It’s still unclear whether or not sleep patterns predict infection, or rather are indicative of an underlying condition that could be causing both poor sleep and susceptibility to infection.

"A likely explanation could be that having an infection leads to disturbed sleep or increased sleepiness, or that both sleep and infection risk is associated with having an underlying disease,” noted Dr. Forthun.

Getting Enough Quality Sleep Each Night

According to Dr. Ramanan, nearly every aspect of sleep is personal. But, in general, most adults need to get between 7 and 8 hours every night. Kids and teenagers need more than that, usually between 10 and 12 hours. 

“It’s never a one-size-fits-all for every person but in general kids are going to need more than adults and everyone has their sweet spot,” he said.

The emphasis should also be on the quality of sleep an individual is getting, not just how much.

For instance, a person who got ‘enough’ sleep may not feel rested due to poor sleep quality—poor sleep quality also appears to increase a person’s risk of getting sick, observed Dr. Forthun.

According to Dr. Ramanan, sleep apnea, getting up during the night to use the bathroom, and being kept up by stress and anxiety are all reasons a person may be sleepy after sleeping 8 hours a night. 

“In total, your hours of sleep may be a lot, but if it’s not good quality, you may be dampening the restorative function sleep has on different parts of the body,” he explained. “People with sleep apnea can sleep 12 hours and still wake up not feeling refreshed because during the night, their breathing is not regular and that’s impacting their sleep quality overall.”

To improve sleep quality, Dr. Forthun advised people to focus on having good sleep hygiene. Dr. Ramanan recommended paying attention to both the way you go to sleep and the way you wake up. 

“How you transition in and out of sleep matters,” Dr. Ramanan explained, noting that turning off devices at bedtime, having a routine, shutting lights off at night, using a white noise machine, and keeping the blinds open during the day can all help the body get better quality sleep.

He also recommended addressing the things in your life that may be causing stress and anxiety—factors that are widely known to disrupt healthy sleep patterns.

In general, it’s also good to avoid exercise or eating close to bedtime, since these activate the body in ways that support wakefulness rather than sleep. Consistently going to bed and waking up at about the same time every day is also a staple of good sleep hygiene. 

“Life is never simple or perfect,” Dr. Ramanan concluded, “but consistency, falling into a routine, even if it’s not the exact same time every day, can be helpful.”

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  1. Forthun I, Eliassen KER, Emberland KE, Bjorvatn B. The association between self-reported sleep problems, infection, and antibiotic use in patients in general practiceFront Psychiatry. 2023;14. doi:10.3389/fpsyt.2023.1033034

  2. National Heart, Lung, and Blood Institute. Sleep deprivation and deficiency.

  3. Oh CM, Kim HY, Na HK, Cho KH, Chu MK. The effect of anxiety and depression on sleep quality of individuals with high risk for insomnia: a population-based study. Front Neurol. 2019;10:849. doi:10.3389/fneur.2019.00849

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