The relationship between sleep, inflammation, immunity and aging is complex, and there is a lot that science is still working to understand about how sleep and inflammation interact. Here are eight big takeaways to help you better understand the sleep-inflammation relationship, and how to optimize your sleep to keep inflammation in check.
1. The sleep-inflammation relationship is a two-way street
Sleep and inflammation have what’s known as a bi-directional relationship. Both how well and how much you sleep affects the function of your immune system and your levels of inflammation. And in turn, excessive inflammation in the body can interfere with sleep.
Sleeping well is one crucial way we to keep unhealthful inflammation in check, slow the aging of cells, limit the outward signs of aging and reduce risks for chronic disease. And reducing chronic inflammation can help you sleep longer, more soundly and more comfortably.
2. Sleep and inflammation share a common regulator
Our sleep is regulated by circadian rhythms, which drive hormones and other physiological changes that cycle us between sleep and wakefulness throughout the 24-hour day. When our circadian rhythms are out of sync, so is our sleep.
Circadian rhythms also regulate our immune system, and with it, our levels of inflammation. When circadian rhythms are disrupted, so is normal immune function. We’re more prone to unhealthful inflammation, and more at risk for its negative effects, from the visible aging of skin to age-related diseases.
Research shows that maintaining healthy circadian rhythms strengthens immune function. And healthy circadian function is key for getting sound, restorative sleep as we age.
One important way to help keep circadian rhythms in sync is to maintain a consistent sleep routine. Our circadian system is sensitive and precise, and it thrives on consistency. Going to bed at the same time and waking at the same time every day reinforces the healthy circadian rhythms that govern both our sleep and our immune function, including inflammation.
3. Too little sleep triggers inflammation…
There’s a strong body of research showing that lack of sleep raises levels of inflammation in the body. Laboratory studies have tested acute, prolonged sleep deprivation—conditions under which sleep is restricted for 24 hours or more—and found this severe degree of sleep loss increases inflammation activity in the body. Scientists have also studied the impact of partial sleep deprivation on sleep—the kind of chronic, insufficient sleep that so many people experience in their daily lives. Many studies show this form of everyday sleep loss also elevates inflammation.
4. …And so does too much sleep
It might surprise you to learn that sleeping too much can also trigger unhealthful inflammation. A 2016 study reviewed more than 70 scientific investigations into the relationship between inflammation and sleep. This research found sleeping excessively raised levels of key inflammatory markers, including C-reactive protein, which is associated with heart disease, high blood pressure and type 2 diabetes.
Our individual sleep needs vary. Most adults need between 7-9 hours a night—consistently. Getting the right amount of sleep to meet your individual needs is one way to help avoid low-grade, systemic inflammation that’s associated with aging and chronic disease. Here’s a sleep calculator that can help you determine your optimal bedtime and get you into a routine of getting the amount of nightly rest that’s right for you.
5. Even a single night of poor sleep can spike inflammation
It’s easy to write off a single night of poor sleep as no big deal. But every night of sleep counts. Research has shown that one night of insufficient sleep is enough to activate pro-inflammatory processes in the body. A 2008 study found that one single night of partial sleep resulted in significantly higher levels of NF-kB, a protein complex that sends a signal to stimulate inflammation throughout the body. Insufficient sleep also increases the activity of other immune system proteins, known as cytokines, that promote inflammation.
Getting a full night of restful sleep—every night—makes a difference at a cellular level, in your body’s ability to keep inflammation in check, and slow the aging process over time. Adopting daily habits and practices of healthy sleep hygiene is the key to creating a sleep routine that delivers for you, night after night.
6. Inflammation creates cortisol problems for sleep
When the body is in a state of chronic inflammation, it over-produces cortisol—and that’s bad news for sleep. Cortisol is an alerting and stimulating hormone, a major “fight or flight” hormone in the immune system arsenal. Cortisol, like most hormones, follows a daily, 24-hour circadian rhythm, rising and falling throughout the waking day before dropping to its lowest level in the early evening. Chronic inflammation keeps cortisol levels elevated, interfering with the nightly drop in cortisol production that we require in order to relax, get drowsy, fall asleep and stay asleep.
Elevated cortisol in the body at night can shorten sleep amounts—by extending the time it takes to fall asleep, and by making you more likely to wake up in the middle of the night. (Too high cortisol can be a cause of those dreaded 3 a.m. awakenings.) And excess cortisol can reduce the quality of sleep, by keeping you in the lighter stages of sleep where you’re more likely to wake throughout the night—and keeping you out of the deepest, most restorative stages of sleep that fuels cellular repair and slows cellular aging.
You can take steps to protect your body’s natural nightly drop in cortisol. Regular exercise (light to moderate in the evening, to avoid a short-term cortisol spike from intense exertion), stress management with mindfulness practices, and limiting nighttime light exposure all support the important nightly decline in cortisol—and they all contribute to better sleep.
7. Stress is a major player in the sleep-inflammation relationship
Stress is a common obstacle to sleep. Many people fall into a difficult cycle: ending the day stressed out, having a hard time sleeping, feeling exhausted and even more stressed the next day—which leads to more problems sleeping.
This chronic sleep-stress cycle does more than make us tired and irritable. Stress is also a trigger for inflammation. At a biological level, our bodies respond to mental and emotional stress as they would to a harmful pathogen, or to a direct physical threat: with a “fight or flight” response that alters immune system functioning and kicks inflammation into higher gear. Over time, chronic stress creates systemic, low-grade inflammation that ages our cells, makes us look and feel older, and makes us more vulnerable to disease.
Sleeping well can work directly to keep inflammation in check by avoiding the pro-inflammatory activity that occurs in the presence of poor, dysregulated sleep. And sleep offers us significant protection against stress, itself a major contributor to chronic inflammation.
I encourage my patients to use simple relaxation exercises throughout the day—and at night before bed—to help with daily stress management. Guided imagery, breathing exercises and other relaxation practices address both the physical and psychological components of stress. These are 5 of my favorite relaxation exercises for sleep. Mindfulness meditation is a proven stress reducer and an excellent daily practice for improving sleep. And studies of meditation have shown that this ancient mindfulness practice is associated with reductions in chronic, systemic inflammation.
8. Gut health matters for both sleep AND inflammation
Problems with gut health contribute to chronic inflammation. What makes a gut unhealthy? Poor diet, stress, some medications, and illness all contribute to imbalances and dysfunction in the gut microbiome.
Poor sleep and disrupted circadian rhythms also weaken gut health. A lack of sufficient, high quality sleep causes changes to the bacterial composition of the gut, decreasing beneficial bacteria and increasing bacteria associated with disease. Sleeping well is one way to help maintain a healthy gut.
And maintaining gut health—by managing stress, exercising, eating a healthy diet that includes prebiotic (fiber-rich) foods—can help you sleep better.
Both those pillars—healthy sleep and a balanced, thriving gut—can work to limit harmful inflammation, and may help to provide long-term protection against accelerated aging and disease.
The tools for improving gut health are many of the same tools that promote great sleep: eating a diet that’s rich and diverse in whole, unprocessed foods (high-fiber and fermented foods are particularly good for the gut), managing stress, exercising regularly, limiting caffeine and alcohol, and getting help with sleep problems (through diagnosis and treatment of any sleep disorders, including sleep apnea).
Chronic, systemic inflammation doesn’t always come with symptoms. Improving sleep is a powerful tool in helping guard against this often silent and damaging form of inflammation.