Chronotype influence on the effects of COVID-19 lockdown on sleep and psychological status in France.

The present study aims to assess the influence of chronotype on lockdown-induced effects on sleep and psychological outcomes. A total of 1671 participants were recruited in France and filled out online questionnaires about their sleeping hours and sleep quality, their chronotype (morning, intermediate, evening type), and their depressive, anxiety and stress symptoms both retrospectively (before lockdown) and currently (during the lockdown). Statistical analyses estimated the chronotype effect on the impact of the lockdown on sleep and psychological outcomes. Results show that during the lockdown, sleep quality decreased, sleep duration increased, and sleep midpoint was delayed and, while fatigue perception decreased, anxiety and depression increased. The decrease in sleep quality varied according to the participants' chronotype. The evening type's sleep quality decreased the most. A similar chronotype effect was also observed on sleep duration and sleep midpoint. Evening-type participants also increased their depressive symptoms. These results suggest that evening-type individuals have lower resilience to lockdown effect on psychological status and sleep pattern.