Originally published on nationalgeographic.co.uk. Click here to read the full article.

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. That was more than two years ago and Thornes, a mother to three teenagers in San Diego, U.S., still struggles to sleep through the night every now and then.

A similar thing happened to her husband during a recent COVID 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 has swept through the global population, so too have reports of sleep disruptions both during an infection and in the weeks and months beyond.

The links between COVID and sleep are still under investigation, but studies show that bacterial and viral infections, in general, interfere with sleep through physical and psychological mechanisms. Recognising the potential for the virus to upset sleep, experts say, can help people get the care they need.