Introduction: March 17, 2020, the great lockdown has been imposed to contain epidemic wave of Covid-19 in the French population with unprecedented restrictions of movement and out-of-home activities for 8 weeks. These constraints had an impact on lifestyle with a diminution of daily physical activity and an augmentation of sedentary behaviours [1]. Moreover, sleep quality and duration were also altered during the first week of lockdown [1]. Furthermore, the health authorities’ guidelines stipulate that 150 minutes of moderate physical activity are needed to promote quality and duration of sleep [2]. To our knowledge no study evaluated those parameters during and after the great lockdown considering stratification by physical activity and sedentary levels. Thus, the objective was to determine the impact of the great lockdown on sleep quality, daytime somnolence and chronotype in active and non-active French adults. Methods: An online national survey has been conducted. Participants were characterised by their level of physical activity and sedentary behaviour declared before lockdown and were stratified into four groups according to current French guidelines [3]: Sedentary/Active (SA); Sedentary/Non-Active (SNA); Non-Sedentary/Active (NSA); Non-Sedentary/Non-Active (NSNA). Sleep was assessed by the Pittsburgh sleep quality index [4], the Epworth sleepiness scale [5] and morningness-eveningness circadian rhythms have been determined by the Hörne and Otsberg questionnaire [6] at different periods: after 3-weeks of lockdown (P1), at the end of lockdown (P2) and one month after the end of lockdown (P3) (start: April 10, 2020; end: June 24, 2020). Participants characteristics, anthropometry, and sociodemographic variables were also reported. Since assumptions of normality and homogeneity of variances were violated, non-parametric tests and linear mixed effect models were performed. Results: A total of 168 participants, 115 women and 53 men (age, 45.0 ± 16.0 years; BMI, 23.0 ± 3.5 kg/m2; 59% were active worker and 92% had an outdoor space) completed sleep and chronotype questionnaires. Twenty two percent were classified as SA, 24% as SNA, 38% as NSA and 34% as NSNA. Although no difference was found regarding sleep quality between the four groups, sleep quality was enhanced between P1 and P3 (p = 0.001) and between P2 and P3 (p = 0.002). Sleepiness score was significantly higher in the SA group than in NSA and NSNA groups (p = 0.003 and p = 0.027, respectively) but no difference was detected between periods. Regarding chronotype, no between-group differences and lockdown effects were detected between P1, P2 and P3. Discussion: Sleep quality was improved from mid- to one-month post-lockdown independent of physical activity and sedentary profiles. This could be partly explained by a decrease in anxiety and depression state and associated with a better concordance between social schedule and individual sleep preferences [7].