Six weeks after a mild case of COVID-19 at the start of the pandemic, Erika Thornes began waking up between 2 and 3 am every night. Unable to go back to sleep, she listened to podcasts, read and scrolled through Twitter before falling asleep at 4 or 5 in the morning.
A similar thing happened to her husband during a recent COVID infection. She suddenly woke her up at 3am every night. Her sleep improved when she stopped testing positive, but the symptom was extreme while it lasted. “I was pretty shocked,” she says. “I knew I was waking up, but I don’t think I fully understood the seriousness of the awakening. ‘”
Nightmares. Sleepless days. Awakenings of panic in the middle of the night. Sleep 18 hours a day. As COVID-19 has spread to the global population, sleep disturbances have also been reported, both during the infection and in the weeks and months thereafter.
The links between COVID and sleep are still under study, but studies show that bacterial and viral infections generally interfere with sleep through physical and psychological mechanisms. According to experts, recognizing the possibility that the virus disrupts sleep can help people get the treatment they need.
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How sleep and the immune system affect each other
Sleep is closely linked to the immune system, a link that is as well known as it is mysterious. Getting enough rest can help prevent infections, according to evidence and observations dating back thousands of years. But infections can also disrupt sleep in complicated ways.
Animal studies show that viruses and bacteria alter both the amount of time spent sleeping and the type of sleep, says John Axelsson, director of the Sleep Laboratory at the Institute for Stress Research at Stockholm University in Sweden. When the researchers injected rabbits or rodents with moderate doses of bacteria or viruses, the animals slept longer. They have a sleep with more non-rapid eye movements, a state of deep rest considered important for recovery (they spend less time in REM sleep, which is full of dreams).
Cytokines, a category of molecules that can stimulate or slow inflammation, appear to play a role in these patterns, Axelsson says. When healthy animals are deprived of sleep, the levels of some pro-inflammatory cytokines in the brain rise, causing the animals to sleep more than normal. When scientists block these cytokines, animals no longer sleep, even if they are sleep deprived.
It’s harder to do the same kind of research on people, and the results are mixed on how sleep changes during illness. But studies suggest that, at least to some extent, inflammatory molecules affect sleep comparable to other animals. In studies conducted in the 1990s and early 2000s, researcher Thomas Pollmächer and colleagues people injected fragments of bacterial cell walls, called endotoxins, and found that mild activation of the immune system increased sleep and improved non-REM sleep.
But once the immune system went into overdrive with increased cytokine levels and disease symptoms, people experienced more sleep disruptions – something not commonly seen in animals. “The inflammatory system increases the urge to sleep,” says Axelsson. “But at the same time, it disturbs sleep if you have a fever.”
To see how respiratory infections affect sleep in humans, Axelsson and colleagues recruited 100 healthy adults to keep a detailed sleep diary after experiencing the first symptoms of a respiratory infection while wearing a sleep monitor on their wrists. Of the 100 volunteers, 28 people fell ill. In general, those people spent more time in bed and slept longer after symptoms began, researchers reported in 2019.
But it wasn’t a restful sleep. Infected people had difficulty falling asleep, waking up more, and having a more restless sleep, especially when they were more symptomatic. As the symptoms subsided, sleep improved. Anecdotally, this is the same pattern reported by many people with COVID: a lot of sleep at first followed by insomnia or other interruptions as they get sick. The physiological drive to sleep more during illness could be adaptive, helping the body fight the invader, Axelsson says.
Why sleep problems continue after COVID infection
For many people, sleep problems don’t end when a person tests negative. To measure how often sleep problems persist, the researchers interviewed more than 650 longtime COVID patients who visited the Cleveland Clinic’s reCOVer clinic between February 2021 and April 2022. Up to six months after infection 41% reported sleep disturbances; a further 7% reported serious anomalies. Black patients, 12% of study participants, were three times more likely to report sleep problems than other ethnic groups, echoing the disparities seen during the pandemic, says Cinthia Peña Orbea, sleep specialist and lead author of the study, which was released in June.
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Cases of post-COVID narcolepsy, excessive sleep, and impersonation have been reported. dream physics with movements like kicking and talking instead of standing still with typical sleep-induced paralysis, says Monika Haack, a psychoneuroimmunologist at Harvard Medical School in Boston, co-author of a 2019 review of the link between sleep and illness.
The Peña Orbea study suggests the long COVID is in line with other chronic diseases in causing sleep problems. About 60 percent of the people with HIV and over 50 percent of the people with hepatitis C experience poor sleep, as well as people with ME / CFS, also called chronic fatigue syndrome. people with inflammatory bowel disease, rheumatoid arthritis and other inflammation-related diseases (all immune disorders) are often sleep deprived.
Haack is studying the details of how sleep disruption interacts with the immune system. In a forthcoming study, she and her colleagues found that disturbed sleep in 24 healthy people leads to the production of more molecules that prolong inflammation and, more importantly, the suppression of molecules that normally stop inflammation. Even after three full nights of recovery sleep, the inflammation persists, primarily emphasizing the need to maintain good sleep.
Taken together, the evidence illustrates that sleep deprivation can cause or exacerbate many symptoms associated with both acute and long-term COVID, including depression, fatigue, and brain fog. These symptoms, in turn, can make sleep difficult. “It’s always two-way,” says Haack. Insomnia, sleep apnea and other disorders, she says, “can reduce the quality, depth, continuity or regularity of sleep and dampen the immune support functions that accompany normal sleep.”
(Related: To what extent can COVID-19 affect our personality?)
Developing drugs for COVID-related sleep disorders?
Ultimately, scientists could develop drugs that affect cytokine levels to improve sleep, says James Krueger, a sleep biochemist at Washington State University in Spokane. But it is a difficult task because the relationship between cytokines and sleep is extraordinarily complex. Some proinflammatory cytokines improve sleep at low concentrations, but at higher concentrations they cause fragmented wakefulness and sleep. There are also anti-inflammatory cytokines, most of which inhibit sleep at low concentrations.
According to Krueger, hundreds of proteins interact to regulate the immune system and other processes. COVID and other infections disrupt these interactions. Targeting those molecules is still a work in progress. “In recent years, some new drugs have been developed for complex behaviors and brain processes such as sleep,” she says. “Time will tell if they are better than previous drugs.”
How to improve sleep after having COVID
Helping people rest better during and after COVID infections begins by recognizing the importance of sleep, Haack says. This can include avoidance drugs that disturb sleepsuch as opioids, and reduce light, noise and repeated awakenings for hospitalized people.
Establishing regular sleep routines with consistent bedtime and waking times is often part of curing insomnia, Axelsson says. It may also be helpful to limit the time spent in bed to increase sleep efficiency and avoid excessive wakefulness.
Haack recommends awareness to reduce stress and anxiety. In the case of her long-term COVID patients, Peña Orbea saw that cognitive-behavioral therapy produced improvements. “With insomnia, the brain is in a state of hyper arousal,” she says; “Let’s try to restore that state of mental excitement.”
Physical activity and fresh air can help a subset of people who may have stopped hanging out due to their illness, Axelsson says. But for many people with prolonged COVID, exercise can cause it severe setbacksstressing the need for individualized medical care if sleep problems persist after COVID.
“Sleep disturbances can be quite normal during acute COVID infection, due to sleep-disrupting symptoms such as pain, cough, or nasal congestion,” says Haack. “If sleep disturbances persist beyond the acute symptom stage or start developing as a new symptom, now is the time to seek help.”
