# Pre-COVID-19 short sleep duration and eveningness chronotype are associated with incident suicidal ideation during COVID-19 pandemic in medical students: a retrospective cohort study

## TL;DR

Short sleep and being a night owl before the pandemic were linked to increased risk of suicidal thoughts during the pandemic in medical students.

## Contribution

This study longitudinally links pre-pandemic sleep patterns and chronotype to incident suicidal ideation during the pandemic.

## Key findings

- Short sleep duration (<7 hours/night) was associated with 4.91x higher odds of incident suicidal ideation during the pandemic.
- Eveningness chronotype was associated with 3.80x higher odds of incident suicidal ideation during the pandemic.

## Abstract

Cross-sectional evidence suggests that sleep problems increased the risk of suicide during the 2019 coronavirus disease (COVID-19) pandemic. However, a lack of longitudinal studies examined the relationship between pre-COVID-19 sleep duration, chronotype and incident suicide during the COVID-19 pandemic. Thus, we examined these associations in a longitudinal study of medical students.

From the Shantou College Student Sleep Cohort, a total of 333 first and second grade medical students (age 19.41 ± 0.82 years, female 61.26%), without suicidal ideation (SI) at pre-COVID-19 period, were followed up during the COVID-19 pandemic. Incident SI was defined by their response to the 9th question from the Beck Depression Inventory. Short sleep duration was defined as less than 7 h/night. The Morningness-Eveningness Questionnaire was used to evaluate the participants’ chronotype. Logistic regression with adjusted odds ratios (AOR) and 95% confidence intervals (95% CI) was used to examine the association between sleep and SI.

The incidence of SI during the COVID-19 pandemic was 5.71%. Logistic regressions with confounding factors adjustment showed that both short sleep duration (AOR = 4.91, 95% CI = 1.16–20.74) and eveningness (AOR = 3.80, 95% CI = 1.08–13.30) in the pre-COVID-19 period were associated with increased risk of incident SI during the COVID-19 pandemic.

Pre-COVID-19 short sleep duration and eveningness predict incident SI during the COVID-19 pandemic in medical students. Prolonging sleep duration may help to decrease SI during major public health crises.