Objective /Background: The goal of the present study was to assess the prevalence and incidence of insomnia in the United States during the COVID-19 pandemic, and whether, among those that contracted COVID-19, insomnia predicted worse outcomes (e.g., symptoms of greater frequency, duration, or severity).
Methods A nationwide sample of 2980 adults living in the United States were surveyed online at two points during the COVID-19 pandemic (T1 = April–June 2020; T2 = January–March 2021). Insomnia symptoms were assessed at both time points using the Insomnia Severity Index (ISI). The T2 survey also asked questions regarding COVID-19 testing and symptoms.
Results The prevalence of insomnia (defined as ISI ≥15) was 15% at T1 and 13% at T2. The incidence rate of insomnia (i.e., new cases from T1 to T2) was 5.6%. Participants with insomnia were not more likely to contract COVID-19 relative to those participants without insomnia. Among those participants in our sample that contracted the virus during the study interval (n = 149), there were no significant group differences in COVID-19 symptom outcomes, with one exception, participants with insomnia were more likely to report a longer symptom duration (insomnia = 24.8 sick days, no insomnia = 16.1 sick days).
Conclusions The present study suggests the prevalence of insomnia in the U.S. population remained high during the COVID-19 pandemic. The data also support that insomnia may be related to experiencing more chronic COVID-19 symptoms. These findings have more general implications for the role of sleep and insomnia on immune functioning.
The COVID-19 pandemic has had an unequivocal negative impact worldwide. To date, nearly 6.6 million COVID-related deaths have been reported as a result of the virus . The pandemic has also led to greater stress related to social isolation and loneliness, unemployment, grief, and fear of contracting the disease. These factors alone would be expected to negatively impact sleep (e.g., greater stress-related acute insomnia) [2e8]. Beyond this, however, the stay-at-home orders, prolonged social confinement, and culture shift to increased work-from-home during the pandemic may also have led to greater instances of insomnia, possibly owing to greater sleep opportunity . That is, several disease- and social-related circumstances have allowed individuals to alter their sleep schedules (e.g., changes in their time to bed or time out of bed) and subsequently increased the amount of time spent in bed or greater variability with respect to sleep timing; both of which may have deleterious short and long term effects on sleep efficiency [10e12]. For example, one study observed sleep patterns among a sample of individuals residing in Italy during different phases of the pandemic and found that, on average, people delayed their bedtime and risetime and increased their time in bed during the lockdowns .
While several studies now support that greater sleep problems have had an adverse impact on people's mental health during the pandemic, it's unclear whether these increased rates of insomnia have adversely affected physical health, including an individual's ability to respond to the SARS-CoV-2 virus. The present data provide some of the first evidence that insomnia may prolong an individual's recovery from COVID-19. While these findings have clear implications for role of sleep during the ongoing pandemic (and mitigating the effects of the virus), they also highlight the importance of continuing to investigate the impact of insomnia on immune functioning. These results, for example, further support what sleep scientists have been advocating for several decades: insomnia is not only bad for your sleep, it's bad for your health [44e46]. Specifically, persistent bad sleep may augment adaptive immunity and compromise the immune system, and as these data suggest, it may not be that the immune system becomes weakened but rather less efficient (resulting in longer illness duration). The clinical implications are clear, it is important to treat insomnia now more than ever. Especially now that there is a threat of pandemic viruses (i.e., we are more vulnerable to future pandemics), but more generally, treating insomnia may reduce the overall burden of disease by increasing resiliency to disease and infection.