Objective/background: Delayed sleep-wake phase disorder (DSWPD) is defined by a delay in the major sleep episode relative to desired or required sleep and wake times. The objectives of this study were to evaluate DSWPD in our population and to compare it with similar clinical data, to analyse gender differences, and to identify possible subpopulations based on circadian timing and alignment.
Patients/methods: 162 consecutive DSWPD patients from a sleep clinic with a median age of 35.5 (24.0) years, 85 (52.5%) males were studied. Patient data were obtained from a clinical interview composed of socio-demographic, life events, daily habits, consumptions, and comorbidities data; and from diaries, actimetry, melatonin and PSG T1. The Dim Light Melatonin Onset (DLMO) was used to define circadian alignment or misalignment.
Results: In our DSWPD cohort, there were gender differences for different age groups (p=0.028). Men were more likely to be single and women more likely to be married (p=0.034). In students, school failure was higher for women (p<0.001); for workers, absenteeism was higher in women (p=0.001). In the circadian aligned (compared to misaligned group), DLMO was later (p<0.001), sleep onset time (p=0.046) was later, total sleep time (p=0.035), and number of sleep cycles (p=0.018) were lower, as measured using PSG T1.
Conclusions: In this clinical population, DSWPD is more prevalent in young men and in middle age women, although with no overall significant differences between genders. There are two different phenotypes of DSWPD: circadian misaligned and circadian aligned. Depression is prevalent in both groups. Better definition, classification and diagnostic criteria for DSWPD are still needed, and targeted therapeutical intervention should be evaluated.
Keywords: Gender differences; circadian misalignment; circadian phase; phase angle; phenotypes.