Previous research indicates that women tend to struggle with insomnia at higher rates both prior to and during the global COVID-19 pandemic; however, not much research has investigated the extent to which insomnia correlates with comorbid problems, including aggression, depression, anxiety, PTSD severity, and alcohol use between the sexes. On a neurobiological level, insomnia could be associated with those mood disorders due to the effects of sleep disturbance on serotonergic and GABA neurotransmission, and males might experience such associations at a lower frequency due to their increased rates of serotonin synthesis. Consequently, we hypothesized that women would demonstrate higher prevalence of the aforementioned comorbidities during COVID than males due to higher rates of insomnia reported in women during COVID.

We surveyed a total of 13,313 adults, with 5,598 females (Mage=36.4, SD=11.9) and 7,654 males (Mage=37.81, SD=12.7) using Amazon Mechanical Turk between April 2020 and April 2021. Insomnia was measured using the Insomnia Severity Index (ISI), while levels of depression, anxiety, PTSD severity, and alcohol use, and aggression were assessed through Patient Stress Questionnaires (PSQs) and the Buss Perry Aggression Questionnaire (BPAQ).

As expected, there were significant positive correlations between ISI and BPAQ (r(13306)=0.364, p<0.0001), PSQ Depression (r(13300)=0.694, p<0.0001), PSQ Anxiety (r(13211)=0.627, p<0.0001), PSQ PTSD (r(13305)=0.444, p<0.0001), and PSQ Alcohol (r(12915)=0.218, p<0.001). The strength of these associations was significantly higher in males than females in almost all categories: aggression (z=4.27, p<0.0001), depression (z=2.41, p=0.016), anxiety (z=3.16, p=0.0016), and alcohol use (z=5.89, p<0.0001) - not significant for PTSD severity (z=1.48, p=0.14).

We found that insomnia was more strongly correlated with comorbid emotional and behavioral problems among males than females. This stands in contrast to our initial hypothesis, as the findings suggest that men who suffer from greater insomnia are more likely to experience those four comorbidities than females. This suggests that sex may play a role in the association between sleep disturbances and other clinical presentations relevant to neuropsychology. Further work will be necessary to identify the neurobiological mechanisms that drive the sex differences in these associations. While the present findings cannot determine the causal direction of the association, it will be crucial to determine the directionality of these associations and the mechanisms that lead to differences in expression between the sexes.