Sleep Is Essential to a Healthy Immune System

You’ve heard the term “sick and tired.” It exists because poor health leaves us feeling both ways.

The connection between sleep and the immune system may seem complex, but you don’t need to master biology to understand that:^1,2

• We all need adequate sleep to maintain healthy immune systems. For adults (ages 18 to 64), that’s 7 to 9 hours of consolidated sleep every night.
• When the immune system becomes activated, it relies on the circadian system to promote sleep to get the job done.

Sleep for a healthy immune system

When we say we’re healthy, what we’re actually saying is that we’ve achieved homeostasis, a balance among the systems of the human body.

Critical to homeostasis: a healthy immune system.

The immune system exists to recognize, defend against, and repair damage from viruses, bacteria, and other foreign invaders that make their way into the bloodstream, either through injury, infection, or chronic illness.²

Sleep has long played a critical role in achieving and maintaining a healthy immune system. When the body launches an immune response, this can affect sleep. You may become drowsy while fighting infection, for instance, because the body requires rest to allow the immune system to work.

If you get good sleep on most nights, you can feel confident you’ve strengthened your immune system’s ability to do its job at a moment’s notice.

How the immune system works

During sleep, your immune system releases proteins called cytokines.

Some of these exist to promote sleep. Others prepare like armies to multiply in the event of an infection, as a response to inflammation, or during periods of stress. They’re the good guys on the front lines battling to maintain your body’s homeostasis.

With adequate sleep, we can greatly enhance the effectiveness of certain cytokines during an immune system response.

T cells use protein to kill infections

Recent research shows that cytokines known as T cells fight pathogens like viruses by using a sticky protein – called integrin – to literally stick to and kill infected cells. Getting good, sound sleep makes integrin stickier, making it easier for the immune system to both overcome the infection and recover more quickly.³

However, if you don’t get adequate sleep, integrin becomes less sticky, and the T cells can’t fight infection as effectively.³

Unfortunately, sleep deprivation can prevent these protective cytokines from multiplying.⁴

Another problem? Poor sleep can also limit the number of other infection-fighting cells and antibodies that participate in a broad immune response.⁴

Stress factors weaken immune function

Poor sleep can also lead to a state of stress. Unfortunately, stress creates other hurdles for an activated immune system.

Think about it: anxiety, infection, injury, pain – these translate into sleepless nights for many. Then, as you toss and turn, your body releases stress hormones like adrenaline into the bloodstream. When this happens during periods of sleep, it can weaken and even neutralize the function of T cells.⁵

Systemic inflammation and OSA

Systemic inflammation can also wreak havoc on the immune system. Ordinary inflammation processes – such as fever, pain, or swelling—support recovery from injuries, infections, and illness in the moment. They’re temporary and clear up after you’re healed.

Inflammation becomes systemic when the body remains in a constant state of inflammation, even in the absence of obvious illness or injury.

People with chronic illnesses live with systemic inflammation. That includes some sleep disorders.

For instance, someone with obstructive sleep apnea (OSA) will develop systemic inflammation because of the apneas they experience all night long, every single night. Insomnia is also linked to systemic inflammation.⁶

• Their blood oxygen dips below what the body needs to function.
• Their heart struggles to pump on less oxygen, so necessary for muscle function.
• Blocked breathing caused by a collapsed airway inspires the release of stress hormones to signal the brain to wake up and start breathing again after each apnea.

Nightly bouts of sleeplessness can cause anxiety, mood swings, and racing thoughts – all of these linked to ongoing stress responses that can weaken the immune system. People with insomnia are more likely to get sick following exposure to a pathogen. Their inability to achieve good recovery sleep while sick just makes matters worse.⁴Restless legs syndrome (RLS) may also pose a negative influence on the immune system.⁷

Help! I can’t sleep!

Life in the 21st century can make sleep a precious commodity. Many people struggle to get enough due to work, family, or social demands. Or, they struggle with undiagnosed or untreated conditions like OSA, restless legs, or insomnia.

Want a healthy immune system? Make sleep a priority.

• Practice good sleep hygiene
• Make lifestyle changes to get 7 to 9 hours of sleep every night
• Ask your doctor to investigate any health problems—including suspected sleep disorders—which could compromise your immune system’s health