(NEXSTAR) – Long COVID comes in many shapes and forms. Some people continue to have shortness of breath for months, while others complain they have trouble focusing or “brain fog.” One long COVID symptom is so commonplace, it might be going undetected: sleep issues.

“Sleep disorders are one of the most common symptoms that patients who suffer from post-acute sequelae of SARS-CoV-2 infection are having these days,” said Dr. Cinthya Pena, a sleep specialist for Cleveland Clinic.

The Centers for Disease Control and Prevention also lists “sleep problems” as a common symptom of long COVID, also called post-COVID conditions.

“So mainly what we are finding is that they complain from insomnia, fatigue, also brain fog, some of them present sometimes circadian rhythm disorders,” said Pena.

A circadian rhythm disorder is when your body’s internal clock isn’t lined up with your environment, explained Cleveland Clinic. That could mean you’re not getting sleepy and staying asleep at night, or you’re feeling really tired during daylight hours.

As with other long COVID symptoms, they could last months, or even years. The symptoms can be mild or severe, depending on the person. While you’re more likely to develop long COVID after a severe COVID-19 infection, it’s also possible to suffer long-lasting issues even after a mild case. Much more research is needed to understand the wide range of symptoms long haulers experience.

Sleep is so vital to your health, that insomnia, circadian rhythm issues and other sleep problems could bleed over into other aspects of your life, the Cleveland Clinic said.

If you think you may have sleep issues related to a past COVID-19 infection – or any other long-haul symptoms – the CDC recommends talking to a doctor. The agency also recommends tracking your symptoms so you can explain to your health care provider the full range of what you’re experiencing.

While living with long COVID can be frustrating, the Cleveland Clinic said treatment has been helpful for some patients.

“This is just from my personal experience that those patients we were seeing a year ago in our clinic, some of them that are already after 10, 12 months of treatment, I can see some of them are improving their sleep issues,” said Pena. “But there is no exact data, or the literature has not revealed how long symptoms are going to last.”

There are studies that look at how long long-haul symptoms can last, but even those can be difficult to draw conclusions from, explained the CDC.

“For example, some studies look for the presence of post-COVID conditions based on self-reported symptoms, while others collect symptoms and conditions recorded in medical records. Some studies focus only on people who have been hospitalized, while others include people who were not hospitalized. The estimates for how many people experience post-COVID conditions can be quite different depending on who was included in the study, as well as how and when the study collected information,” the agency said.

Based on the information we have now, the CDC estimates about 13% of people who get COVID-19 still experience symptoms one month after infection. That drops to 2.5% three months or more after infection.

The odds of getting long COVID are much higher if you were hospitalized. The CDC estimates more than 30% of people hospitalized for the virus are still experiencing symptoms six months later.