How Does Lack of Sleep Affect Your Immune System?

Lack of sleep and your immune system

Your immune system is made up of an army of immune cells that fight viruses and other foreign invaders. Two other components, bone marrow, and an organ near the heart called the thymus, play a key role in helping T and B-lymphocytes, two types of immune cells mature. Once they’re “all grown up”, these cells travel to lymphoid tissue where they lie in wait for any threats. If all goes well, these cells spring into action when challenged by an invader and prepare to take down the enemy. Hopefully, they win the battle!

The downside is that immune function becomes more sluggish with age, and several other lifestyle factors can diminish your immune system’s ability to fight viruses. For example, older people have immune systems that don’t respond as robustly to invaders. Since cancer cells are another type of foreign invader, this partially explains why the risk of cancer goes up with age and the fact that older people are more likely to die of viral infections, including influenza. You can’t do much about your age, but other factors have an impact too. One of them is sleep.

Sleep and Immunity

Sleep is important for a healthy immune function! You need adequate sleep to reboot your brain and to stay metabolically healthy, but how much time you slumber and the quality of that sleep also affects your immune system.

In fact, a study published in the Journal of Experimental Medicine found that getting a good night’s sleep helps immune cells called T-cells fight viruses and bacteria more effectively. T-cells are one of the body’s chief defenses against viruses. These specialized cells, once they recognize a protein on a virus, release a variety of toxic chemicals that help take down the virus. However, viruses are clever. They have stealth ways of going undercover and hiding from T-cells. But if you sleep enough to maximize T-cell function, you have better odds of fighting off viruses.

There’s another way sleep impacts immunity. Studies show that without adequate sleep, cells produce fewer cytokines, chemicals that fight viruses and reduce inflammation. Immune cells release cytokines when cells are damaged, and this galvanizes other immune cells. It’s during sleep that your body makes and releases more cytokines, so when you shortchange yourself on sleep, you have fewer defenses against infection and inflammation.

Studies also show that lack of sleep makes natural killer cells, also known as NK cells, less active. When NK cells aren’t as energetic, it indicates a weakened immune system. In one study, participants who had their sleep disrupted experienced reduced NK cell activity. This would place them at higher risk of infection, including viral infections. So, sleep disruptions and poor-quality sleep may also harm immune system function.

How Much Sleep Do You Need?

The National Sleep Foundation’s panel of experts reviewed over 300 studies dealing with sleep and health. From these findings, they concluded that the amount of sleep a person needs depends on age and the amount may vary with the individual. We know that children and teenagers need more than adults, but the optimal amount of sleep doesn’t change much once you become an adult. Young adults and older adults still need between 7 and 9 hours of sleep each night.

When you fall below 7 hours of sleep per night routinely, it ramps up your “fight or flight” nervous system and that can lead to problems like anxiety, a fast pulse rate, and elevations in blood pressure. If you get less than 7 hours of sleep for 3 nights in a row, it has similar health effects to missing a full night of sleep.

What if You Fall Behind on Sleep?

Being deprived of sleep isn’t good for your immune system or your health, but what if you have a night of interrupted sleep and end up shortchanged on sleep? Make time for a nap? Studies showing that taking only two 30-minute naps per day can make up for the negative impact of a night of poor sleep. Research shows that lack of sleep also increases the risk of other health problems, including cardiovascular disease, type 2 diabetes, and obesity.

Plus, poor quality or too little sleep causes changes in mood and brain function too. You might experience memory issues, poor judgment, and feel anxious or down, not to mention tired! To add to the problems, lack of sleep affects appetite hormones too, so you feel hungrier and make less healthy food choices. Therefore, it’s not surprising that research links poor quality sleep and lack of sleep with obesity.

The Bottom Line

Sleep matters for health and for the wellbeing of your immune system. If you’re getting less than 7 hours of sleep per night, you’re shortchanging the immune forces that protect against viruses. So make getting a good night’s sleep a top priority. Here are some tips for getting a better night’s sleep:

  • Go to bed and wake up at the same time each night, even on weekends.
  • Avoid exposing your eyes to blue light from technology within 2 hours of bedtime.
  • Dial back the temperature of your sleeping area to between 62 and 65 degrees F.
  • Avoid eating before bedtime and keep the evening meal light.
  • Take a hot bath before heading off to sleep.
  • Avoid caffeine after 12:00 p.m.
  • Avoid alcohol.
  • Remove light from your sleeping area by installing light-blocking curtains or by wearing a sleep mask.
  • Work out in the morning and do something relaxing after dinner.
  • Check your medications with your doctor to make sure they aren’t contributing to poor sleep quality.


If you have persistent problems falling asleep, get a full physical exam. Problems sleeping can be caused by a common condition called sleep apnea. Undiagnosed sleep apnea can be harmful to your health.



  • org. “How Much Sleep Do We Really Need: Revisited”
  • com. “How Sleep Strengthens Your Immune System”
  • Medical News Today. “How sleep can boost your body’s immune response”
  • Exp Med (2019) 216 (3): 517–526.
  • FASEB J. 1996 Apr;10(5):643-53.
  • com. “Natural Killer Cells Need A Good Night’s Sleep”
  • Center for The Advancement of Health. “Natural Killer Cells Need A Good Night’s Sleep.” ScienceDaily. ScienceDaily, 26 January 1998.


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