Short Sleepers with Pre-Existing Medical Conditions at Higher Risk of Long COVID

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A new study found the risk of Long COVID for short sleepers with pre-existing medical conditions was 3-fold higher than average-length sleepers without pre-existing conditions.

Individuals with habitual short sleep duration and pre-existing conditions have a higher risk of Long COVID, according to a new study.

“We found that prior-infection habitual short sleepers with pre-existing medical conditions had a higher likelihood of Long COVID,” the investigators wrote.

Previous research suggested the risk for Long COVID is higher among people with pre-existing medical conditions. Investigators, led by Linor Berezin, MD, of the department of anesthesia and pain management at the University of Toronto, wanted to explore the association between the risk for Long COVID and pre-existing conditions, as well as see if the association varies by habitual sleep duration.

Approximately 40% of individuals develop Long COVID and may have symptoms of fatigue, dysgeusia, dyspnea, asthenia, persistent cough, muscle aches, depression, anxiety, cognitive dysfunction, and sleep problems. A greater incidence of Long COVID exists in individuals with greater BMI, older age, female sex, pre-existing medical conditions, and severe COVID-19. Pre-existing medical conditions include chronic cardiac diseases, chronic respiratory diseases, chronic neurological conditions: autoimmune conditions and cancer, allergies, endocrine disorders, chronic, and psychiatric conditions.

The cohort included 16,899 participants ≥ 18 years old, with 2508 participants diagnosed with COVID-19 at some point. More than half (61%) reported ≥ 1 Long COVID symptom. Participants filled out a questionnaire, designed by the International COVID Sleep Study II group, which asked for sociodemographic variables (age, sex, BMI), if they tested positive to COVID, persistent COVID-19 symptoms, and sleep duration.

Of the 1,542 participants who reported having Long Covid, 945 participants reported having pre-existing medical condition. The investigators found long sleepers were significantly younger (36.0 ± 14.7 years, P < .001) in comparison to short sleepers (44.5 ± 13.8 years) and those with average sleep duration (43.9 ± 13.5 years). Moreover, long sleepers and average-duration sleepers were 90% and 86.6% White, respectively.

Short sleepers also had a significantly greater number of individuals with asymptomatic COVID-19 (6.3% vs 6.1% vs 9.6%, P = .002) and severe or life-threatening COVID-19 (8.5% vs 6.1% vs 12.2%). Furthermore, the team noted significantly more individuals with pre-existing cardiac conditions among habitual short sleepers (33.6%) compared to average (18.7%) and long sleepers (6.6%) (P < .001)

A multivariable logistic regression analysis demonstrated the Long COVID risk was 1.8-fold higher for average-length sleepers (6 – 9 hours a night) with pre-existing medical conditions compared to individuals without pre-existing medical conditions (adjusted odds ratio [aOR], 1.84; 95% CI, 1.18 – 2.90; P = .008).

As for short sleepers with pre-existing medical conditions, the risk of Long COVID was nearly a 3-fold higher (aOR, 2.95; 1.04 – 8.4; P = .043) than average-length sleepers without pre-existing conditions. When compared to average-length sleepers without pre-existing conditions, the Long COVID risk was not significantly higher for long sleepers with pre-existing conditions (aOR, 2.11; 0.93 – 4.77; P = .073).

“Our findings suggest that habitual short sleep duration may modulate the relationship between Long COVID and pre-existing medical conditions, and the interplay between sleep duration and pre-existing medical conditions may play an important role in the pathogenesis of Long COVID,” the team concluded.


  1. Berezin L, Waseem R, Merikanto I, et al. Habitual short sleepers with pre-existing medical conditions are at higher risk of Long COVID. J Clin Sleep Med. 2024;20(1):111-119. doi:10.5664/jcsm.10818
  2. Risk of Long COVID In People with Pre-Existing Conditions Is Higher Among Short Sleepers. American Academy of Sleep Medicine. January 11, 2024.