COVID-19 can ruin your sleep in many different ways—here's why

Six weeks after a mild case of COVID-19 early in the pandemic, Erika Thornes started waking up every night between 2 and 3 a.m. Unable to fall back asleep, she would listen to podcasts, read, and scroll through Twitter before finally dozing off by 4 or 5 a.m. Thornes, the mother of three teenagers in San Diego, continued to struggle to sleep through the night for more than two years after that—a pattern that improved only after she started taking a new medication following her second bout with the virus in the summer of 2023.

A similar thing happened to her husband during a COVID-19 infection. He was suddenly waking up at 3 a.m. every night. His sleep improved when he stopped testing positive, but the symptom was extreme while it lasted. “He was quite shocked,” she says. “He knew I was waking up, but I don’t think he quite understood the severity of ‘awake.’”

Nightmares. Days without sleep. Waking in a panic in the middle of the night. Sleeping for 18 hours a day. As COVID-19 swept through the global population, so too did reports of sleep disruptions both during an infection and in the weeks and months beyond.

Studies published since the pandemic began have revealed new details about how the virus altered sleep and have documented the general ways that bacterial and viral infections interfere with sleep through physical and psychological mechanisms. New research has also revealed how poor sleep during and after COVID-19 can exacerbate many symptoms of both acute and long COVID—including brain fog—and how insomnia can lower production of antibodies after vaccination.

Recognizing the potential for SARS-CoV-2—the virus that causes COVID-19—to upset sleep, experts say, can help people get the care they need.

How sleep and the immune system affect each other

Sleep is intricately entwined with the immune system, a link both well-known and still mysterious. Getting enough rest can help prevent infections, according to evidence and observations going back thousands of years. But infections can also disrupt sleep in complicated ways.

Studies in animals show that viruses and bacteria alter both the amount of time spent sleeping and the kind of sleep, says John Axelsson, director of the Sleep Laboratory at Stockholm University’s Stress Research Institute in Sweden. When researchers inject rabbits or rodents with moderate doses of bacteria or viruses, the animals sleep more. They get more non-rapid eye movement sleep, a deep restful state thought to be important for recovery; and they spend less time in dream-filled REM sleep.

Cytokines, a category of molecules that can stimulate or slow down inflammation, appear to play a major role in these patterns, Axelsson says. When healthy animals are sleep deprived, levels of some pro-inflammatory cytokines in the brain rise, causing the animals to sleep more than usual. When scientists block these cytokines, animals don’t sleep more—even when they are sleep deprived.

It’s harder to do the same kind of research in people, and results are mixed about how sleep changes during illnesses. But studies suggest that, at least to some extent, inflammatory molecules affect sleep in ways comparable to other animals. In studies from the 1990s and early 2000s, researcher Thomas Pollmächer and colleagues injected people with bits of bacterial cell walls, called endotoxins, and found that mild activation of the immune system increased the drive for sleep and enhanced non-REM sleep.

But once the immune system revved up with increased cytokine levels and symptoms of illness, people experienced more disrupted sleep, not typically seen in animals. “The inflammatory system increases the drive for sleeping," Axelsson says. “But at the same time, it then disrupts your sleep if you get a fever.”

To see how respiratory infections affect human sleep, 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-tracking device on their wrists. Of the 100 volunteers, 28 people got sick. Overall, those people spent longer in bed and slept more after their symptoms began, the researchers reported in 2019.

But this wasn’t a restful sleep. Infected people had difficulty falling asleep, woke up more, and had a more restless sleep especially when they were most symptomatic. As symptoms eased, sleep improved. Anecdotally, that’s the same pattern reported by many people with COVID-19—a lot of sleep initially followed by insomnia or other disruptions while sickest. The physiological drive to sleep more while getting sick might be adaptive—helping the body fight off the invader, Axelsson says.

Why sleep problems continue after COVID infection

For many people, sleep troubles don’t end on Day 10 or when a person tests negative. To gauge how often sleep troubles persist, researchers surveyed more than 650 long COVID patients who visited the Cleveland Clinic’s reCOVer Clinic between February 2021 and April 2022. Up to six months after an infection, 41 percent reported sleep disturbances; an additional 7 percent reported disturbances that were severe. Black patients, 12 percent of study participants, were three times more likely to report sleep problems compared with other groups—echoing disparities seen throughout the pandemic, says Cinthia Peña Orbea, a sleep specialist and lead author of the study, which was published in June.

Elsewhere, there have been reports of post-COVID-19 narcolepsy, excessive sleeping, and physically enacting dreams with movements like kicking and talking instead of lying still with typical sleep-induced paralysis, says Monika Haack, a psychoneuroimmunologist at Harvard Medical School in Boston, who co-authored a 2019 review of the links between sleep and disease.

Peña Orbea’s study suggests that long COVID-19 falls in line with other chronic illnesses for causing sleep issues. About 60 percent of people with HIV and more than 50 percent of people with hepatitis C experience poor sleep as do people with ME/CFS, also called chronic fatigue syndrome. People with inflammatory bowel disease, rheumatoid arthritis, and other inflammation-related diseases—all immune disorders—often suffer from lack of sleep.

You May Also Like

SCIENCE

Now we know how COVID attacks your heart

SCIENCE

Multiple COVID infections can lead to chronic health issues. Here’s what to know.

SCIENCE

Why does COVID-19 cause brain fog? Scientists may finally have an answer.

Sleep disorders appear to be common after severe cases of COVID-19, according to new evidence. Among survivors who were admitted to the ICU, put on ventilators, or had extreme symptoms like a very low oxygen levels, a third had ongoing sleep disorders after recovering from their illness, found a 2023 review of 16 studies that included more than 10,500 people.

A direct link from insomnia to respiratory illness

Although getting a good night sleep has long been standard advice for staying healthy, there hadn’t been large studies to assess whether insomnia directly boosted the risk of getting sick, says Hanna Ollila, who studies sleep at the University of Helsinki and Massachusetts General Hospital. To fill the gap, she and colleagues turned to two databases containing health records from 558,000 people in Finland and the U.K.

Ollila’s team reported in 2023 that that a prior diagnosis of insomnia increased the later risk of developing an upper respiratory infection, influenza, and COVID-19. For COVID, the data suggested that insomnia made people more susceptible to developing severe illness rather than making them more vulnerable to infection. “The connection between sleep and infections has been a question in many earlier studies,” Ollila says. The new study, she says, helps draw a line from sleep disruption to risk of getting sick.

Again, inflammation appears to help explain the link. In a 2022 study, Haack and colleagues found that disturbing sleep in 24 healthy people led to the production of more molecules that prolonged inflammation and notably, a suppression of molecules that normally stop that inflammation. Even after three full nights of recovery sleep, inflammation persists, emphasizing the need to preserve good sleep in the first place.

Sleeplessness can cause or exacerbate many symptoms associated with both acute COVID and long COVID, including depression, fatigue, and brain fog. Those symptoms in turn can make it hard to sleep. “It's always bi-directional,” Haack says. Insomnia, sleep apnea, and other disruptions, she says, “all can lower sleep quality, depth, continuity, or regularity, and dampen the immune supporting functions that come with normal sleep.”

Sleep is also important to get maximum benefits from vaccines, says Nikolaos Athanasiou, a pulmonologist at the University of Athens, Greece. Among 544 healthcare workers who hadn’t previously been infected with the SARS-CoV-2 virus, those with insomnia produced lower levels of antibodies in response to the COVID-19 vaccine. “It has not been pointed out enough,” Athanasious says, “that sleep deprivation and reduced sleep duration decreases immune response.”

Developing drugs for COVID-related sleep disorders? 

Ultimately, scientists might be able to develop medications that affect levels of cytokines to improve sleep, says James Krueger, an expert on the biochemistry of sleep at Washington State University in Spokane. But it’s a challenging task because the relationship between cytokines and sleep are extraordinarily complex. Some pro-inflammatory cytokines enhance sleep at low concentrations but at higher concentrations, they lead to wakefulness and fragmented sleep. There are also anti-inflammatory cytokines that mostly inhibit sleep at low concentrations.

Hundreds of proteins interact to regulate the immune system and other processes, Krueger says. COVID-19 and other infections tweak those interactions. Targeting those molecules remains a work in progress. "For complex behaviors and brain processes such as sleep, some new drugs have been developed over the past few years,” he says. “Time will tell if they are better than prior drugs.”

The impact of psychological stress

A better understanding of how infections affect sleep in biological ways will develop with more trials and better data, Axellson says. In the meantime, a slew of studies suggests that stress, disruption in routines, mental health, and other non-physiological factors related to illness also affect sleep.

During lockdowns, 57 percent of people reported poor sleep quality, found a 2020 survey by Italian researchers. Overall, people spent a longer time in bed while quarantined, studies show. But they didn’t sleep as well as before they were confined to their homes and isolated from others, and their dreams became more vivid, bizarre, and emotionally intense.

For many people, those issues persisted even after lockdowns ended, as people started getting out more and feeling less stressed, Italian researchers reported in 2021. The researchers speculated that for many people—including children—psychological distress lingered past the acute phase of the pandemic. A 2023 study by researchers in Spain found that sleep quality declined during lockdowns among kids, ages 5 to 9. Like adults, their sleep hasn’t bounced back since, possibly because of ongoing anxiety and a persistent increase in screen time.

How to improve sleep after COVID-19

Helping people get better rest during and after COVID-19 infections begins with acknowledging the importance of sleep, Haack says. That can include avoiding medications that disturb sleep, such as opioids, and reducing light, noise, and repeated wakeups for people who are hospitalized.

Establishing regular sleep routines with consistent bedtimes and wakeup times are often a part of insomnia care, Axelsson says. It can also help for people to restrict time in bed to increase sleep efficiency and avoid excessive time spent lying awake.

Haack recommends mindfulness apps to reduce stress and anxiety. For her long COVID-19 patients, Peña Orbea has seen cognitive behavioral therapy led to improvements. “With insomnia, the brain is in a hyper-arousal state,” she says. “We try to reset that arousal state of mind.”

Physical activity and being outside in daylight can help a subset of people who may have stopped going out because of their illness, Axelsson says. But for many with long COVID, exercise can cause serious setbacks, underscoring the need for individualized medical care if sleep problems persist post-COVID.

“Sleep disruption can be quite normal during the acute COVID infection, due to sleep-disrupting symptoms such as pain, coughing, stuffy nose,” Haack says. “If sleep disturbances continue to stay beyond the acute symptomatic phase or start to develop as a new symptom, that is the time to seek help.”