Why Is Sleep So Important for a Healthy Immune System?

“There’s a lot of truth to the idea that sleep is the best medicine,” says Filip Swirski, PhD, a professor of medicine at the Icahn School of Medicine at Mount Sinai in New York City, who has studied the relationship between sleep and the immune system.

“We know that sleep disruption affects the rhythm and production of immune cells, and if there is a challenge to the immune system (such as an infection or injury), a single night of poor sleep can affect the response,” he says.

What Does Your Immune System Do?

But when you’re not getting enough sleep, your immune system and inflammatory responses are disrupted, which can negatively affect your health.

How Does a Lack of Sleep Affect the Immune System?

Sleep allows your body the opportunity to replenish its immune cells. “These cells are the foot soldiers of the immune system,” Swirski says. “They survey for potential threats and participate in host defense.”

The production of immune cells mostly takes place when you’re sleeping, not when you’re awake, he explains. And when you don’t get adequate sleep, this production is thrown out of whack.

When that happens, one of the consequences can be out-of-control inflammation. “Sleep disturbances or sleep loss can produce a marked increase in inflammation,” says Michael Irwin, MD, a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at UCLA in Los Angeles, who has conducted years of research on sleep and the immune system.

While healthy inflammation can help the body defend itself from threats, Dr. Irwin says that too much inflammation can contribute to the kinds of internal damage or changes that lead to heart disease, diabetes, and some other medical conditions, all of which research has also linked to poor sleep. Too much inflammation can also increase pain, swelling, and other symptoms of chronic diseases, he says.

One night of poor sleep likely won’t make or break your health. But it’s clear that if you aren’t sleeping well much of the time, your health is likely to suffer.

4 Sleep Tips for Healthy Immune Functioning

Now that you know sleep deprivation can negatively affect your immune system and overall health, you may want to know what you can do to improve your sleep habits and boost immunity. Here are some tips to consider.

1. Focus on Sleep Quality

“Sleep duration is not as big a predictor of inflammation as poor sleep quality,” Irwin says. “We found that you really don’t see an increase in inflammation until you get down to the five- to five-and-a-half-hour range.”

He also says that, even if people are sleeping a solid eight hours a night, that doesn’t necessarily mean that their sleep is deep and supportive of a healthy immune system. “Even among people with adequate sleep duration, if they wake up feeling tired, they report that they’re waking up a lot during the night, or the quality of their sleep is poor, we find all that is associated with increases in inflammation,” he says.

He says one of the best ways to assess your sleep is to ask yourself how you feel in the hours after you wake up. If you feel rested and rejuvenated, that’s a sign that you had a good night’s sleep. “People also turn to devices like Fitbits and Apple watches to assess their sleep, and I’ve found they’re actually very good at determining the quality of your sleep,” he says.

2. Set a Consistent Sleep Schedule

If you want to strengthen your sleep in order to support your immune system, Irwin offers advice that you’ve probably heard elsewhere. “Stick with a consistent sleep-wake routine, get some exercise during the day, and avoid alcohol and caffeine before bed,” he says.

3. Try Practicing Mindfulness

4. Seek Professional Support

If sleep is a struggle, especially if you are snoring, a mouth breather, or at risk for sleep apnea, it's best to discuss these concerns with your healthcare provider. They can help you understand why you’re not sleeping well or refer you to a sleep medicine specialist.

Cognitive behavioral therapy for insomnia, or CBT-I, has proven itself to be one of (if not the) safest and most effective insomnia treatments, Irwin says. It’s recommended as a first-line treatment for people with insomnia. Unfortunately, he says there is a lack of qualified CBT-I therapists — not nearly enough to meet demand. “We have a 2,000-person waitlist at our clinic, so it’s a big issue,” he says.

The Takeaway

• Your immune system is responsible for fighting off pathogens and illnesses, and for keeping your body healthy.
• Not getting enough sleep can affect how well your immune system can fight infections and diseases.
• Sleep deprivation can increase your risk of developing health conditions like high blood pressure, obesity, and depression.
• You can improve your sleep habits by focusing on sleep quality, setting a consistent sleep schedule, and practicing mindfulness.