Social timing influences sleep quality in patients with sleep disorders

We aimed to compare three variants of the Pittsburgh Sleep Quality Index (PSQI usual, work- and work-free days: PSQI_u, PSQI_w, PSQI_f) and to assess whether chronotype (MSF_sc)/social jetlag (SJL) are associated with sleep quality in patients with sleep disorders (SD).

In sum, 431 SD patients and 338 subjects from the general population (GP) were included. Participants filled in three variants of the PSQI and the Munich ChronoType Questionnaire (MCTQ). We used Generalized Estimating Equations (GEE) to investigate effects of group (GP, SD), PSQI (usual, work or free) and their interaction (group∗PSQI) on scores. To investigate associations between MSF_sc/SJL and the difference between PSQI_w and PSQI_f (PSQI_diff) in patients with SD we used linear regressions (N = 352). We used Sobel to test whether there was a mediation effect of SJL on the association between MSF_sc and PSQI_diff.

PSQI scores differed between groups (p < 0.001). Post-hoc analysis revealed a significant difference between PSQI_u vs. PSQI_f and PSQI_w vs. PSQI_f with PSQI_f presenting lower scores, while PSQI_u vs. PSQI_w did not differ in any group. In line with previous findings, SJL was associated to PSQI_diff in SD patients.

PSQI_u mainly represents sleep quality on workdays also in SD patients. Being a late chronotype seems to be associated with higher differences in sleep quality on work-vs. free days mostly when it coincides with societal time constraints. Since sleep quality is poorer on workdays even in SD patients, we suggest that treatment strategies should address social aspects affecting sleep, including ways of minimizing SJL.