Long COVID May Cause Fatigue, Brain Fog, Poor Sleep, Study Finds


Patients with post-acute COVID syndrome, or “long COVID,” can experience symptoms for at least 12 months, investigators reported.

Patients may experience symptoms related to post-acute COVID syndrome (PACS), also referred to as “long COVID,” for at least 12 months after initial COVID-19 infection, according to a recent study.1

The research, published in the American Journal of Physical Medicine and Rehabilitation, also demonstrated the negative impacts of PACS symptoms on physical function, cognitive function, health-related quality of life, and participation.1,2 The study is one of the first to measure the impairment and impact of PACS on patients and note the factors that exacerbate symptoms.2

PACS is one of the most troubling manifestations of severe COVID-19 infection and can last for several months, according to investigators.1 “Despite the highly debilitating nature of PACS, the long-lasting symptoms often occur in the absence of severe acute infections, medically explainable physical symptoms, or pre-existing comorbidities,” the authors wrote.

Recent studies have identified the most common persistent symptoms of severe COVID-19 infection. These include:

  • Fatigue
  • Dyspnea
  • “Brain fog”/various cognitive symptoms
  • Pain
  • Anxiety
  • Depression
  • Gastrointestinal issues

Researchers have observed that a COVID-19 infection acts like an immune trigger, which may be the cause of the persistent symptoms.

The cross-sectional, observational study surveyed a total of 156 patients who were not yet vaccinated for COVID-19 at the Mount Sinai PACS Clinic between March 2020 and March 2021.

Among the survey respondents, 82% reported fatigue (n=128), 67% said they experienced brain fog (n=105), 60% suffered headaches (n=94), 59% experienced sleep disturbance (n=92), and 54% reported dizziness (n=85).

Physical exertion (86%), stress (69%), and dehydration (49%) were the most common triggers of symptom exacerbation, the researchers found. Other triggers included weather changes (37%), consuming large meals (28%), premenstrual period (22%), and alcohol consumption (22%).

Investigators also reported that 78% of patients indicated problematic fatigue, and 40% of patients showed moderate to severe disability due to dyspnea. Compared with pre-COVID-19 infection, patients were completing at least 150 minutes per week of physical activity on a less frequent basis.

Sixty-three percent of patients indicated experiencing at least mild cognitive impairment, while another 19% exhibited symptoms of a possible anxiety disorder and 28% showed signs of major depressive disorder.

Study limitations include the use of clinical survey data, the retrospective nature of the research, and a lack of either a comparison group or pre-COVID-19 infection data.

“It is clear that in the wake of the COVID-19 pandemic, a second, longer term public health emergency has emerged,” authors concluded. “It is imperative to understand the burden of this novel condition with millions [of] Americans at risk of developing PACS by the end of the pandemic.”


  1. Tabacof L, Tosto-Mancuso J, Wood J, et al. Post-acute COVID-19 syndrome negatively impacts physical function, cognitive function, health-related quat lity of life and participation. Am J Phys Med Rehbail. Published online October 20, 2021. doi: 10.1097/PHM.0000000000001910
  2. Long COVID can negatively impact physical and cognitive function, employment, and quality of life for at least one year. News Release. EurekAlert; October 25, 2021. Accessed November 4, 2021. https://www.eurekalert.org/news-releases/932580.

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