The Surprising Link Between Sleep and Inflammation

At a glance, sleep and inflammation may seem unrelated. Sleep is generally considered beneficial, whereas inflammation often carries a negative connotation. Yet, the processes governing sleep are deeply impacted by chronic inflammation, and vice versa. “Sleep and the immune system and inflammation are closely connected,” says Sarathi Bhattacharyya, M.D., a pulmonologist, sleep medicine specialist, and medical director of MemorialCare Sleep Disorders Center at Long Beach Medical Center in Long Beach, CA .

How Inflammation Impacts Sleep

Chronic inflammation can significantly disrupt sleep. “Chemical signals that are activated in inflammation can disrupt normal sleep architecture, causing sleep fragmentation. This can lead to unrefreshing sleep and sleepiness or fatigue during the day,” explains Morgan Soffler, M.D., an assistant professor of pulmonary, critical care, and sleep medicine at New York Medical College. These chemical signals, called cytokines, are small proteins released by the immune system during an inflammatory response.

“These proteins serve as messengers for specific functions, including sleep regulation,” explains Ana Krieger, M.D., M.P.H., the director of the Center for Sleep Medicine at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine. Some cytokines promote wakefulness, while others aid sleep. However, during chronic inflammation, cytokine production becomes disrupted, leading to jumbled signals that worsen sleep. “Elevated cytokines cause symptoms that mimic those of sleep disorders and affect the quality of sleep,” says Dr. Bhattacharyya. Studies have shown elevated cytokine levels in individuals with insomnia, sleep apnea, and chronic fatigue syndrome.

Inflammation can also interfere with hormone production in the brain, impacting sleep-wake cycles. “Hormones such as serotonin and dopamine are affected by inflammation, and their disruption can cause sleep fragmentation and less restorative sleep,” says Dr. Soffler. Symptoms of chronic inflammation, like muscle aches, joint pain, headaches, and gastrointestinal issues, can prevent sleep or cause awakenings during the night .

Can Poor Sleep Increase Inflammation?

Just as chronic inflammation can hinder restful sleep, insufficient sleep can also increase inflammation. “Lack of adequate sleep may affect immune function regulation. For example, inflammation causes sleep loss, and inadequate or insufficient sleep triggers a systemic increase in inflammatory mediators, perpetuating the problem,” explains Dr. Krieger.

Sleep deprivation may also increase cytokine production. “Studies in rodents have shown that sleep loss or deprivation can lead to changes in the blood-brain barrier and allow more inflammatory molecules to cross into the brain,” says Dr. Bhattacharyya. Poor sleep is often associated with lower levels of melatonin, a hormone regulating the sleep-wake cycle. “Interestingly, melatonin has been shown to have some anti-inflammatory effects,” says Dr. Soffler. A drop in melatonin levels with poor sleep diminishes these anti-inflammatory properties, potentially increasing inflammation.

A review published in Communications Biology found that poor sleep leads to a chronic inflammatory state, increasing the risk of cardiometabolic, autoimmune, and neurodegenerative conditions.

How to Support Sleep and Lower Inflammation

Lifestyle strategies can improve sleep and reduce inflammation. “A holistic approach to improve our health and wellbeing can significantly impact the effects of inflammation on sleep. Also, by improving sleep, the inflammatory response may be attenuated, making it easier to cope with,” affirms Dr. Krieger.

Key strategies include:

• Regular Physical Activity: Aim for at least 150 minutes of moderate-intensity exercise per week, as recommended by the Centers for Disease Control and Prevention.
• Better Sleep Hygiene: Maintain a regular bedtime and morning routine, practice relaxation techniques, and ensure a conducive sleep environment.
• A Healthier Diet: Minimize ultra-processed foods and excessive alcohol consumption.
• Stress Reduction: Incorporate mind-body activities like yoga or tai chi.
• Addressing Underlying Sleep Disorders: Seek medical attention and treatment for sleep disorders like sleep apnea.