O019 Sleep irregularity doesn’t predict mental health in sleep-disordered young adults

Abstract Introduction Irregular sleep is associated with poor mental health in healthy young adults; however, whether these associations extend to young adults with unmanaged sleep disorders remains unclear. We aimed to explore associations between sleep irregularity and anxiety and depressive symptoms in young adults with and without insomnia or delayed sleep–wake phase disorder (DSWPD). Methods 61 participants (60% female, mean + SD age = 30.0 ± 5.1y) monitored their sleep for up to three weeks using sleep–wake diaries and Withings Sleep Analyzers. Insomnia and DSWPD diagnoses were determined by a psychologist per DSM-5-TR criteria. Sleep irregularity was measured using the Sleep Regularity Index (SRI). The Generalised Anxiety Disorder (GAD-7) and Patient Health Questionnaire (PHQ-9) were used to assess anxiety and depression symptoms, respectively. Bootstrapped regressions were used to determine associations between SRI and mental health symptoms. Results 43% of participants had insomnia, 34% had DSWPD, and 23% were healthy sleepers. Compared to healthy sleepers (Median SRI = 78.6), the SRI was lower, indicating greater irregularity, in those with DSWPD (75.3, p=.02) but did not significantly differ from those with insomnia (77.2, p=.26). SRI predicted neither depressive nor anxiety symptoms for insomnia (p=.95; p=.49, respectively) or DSWPD (p=.85; p=.57). Discussion Young adults with DSWPD had greater sleep irregularity than healthy sleepers. This likely reflects their delayed sleep–wake patterns when their schedule permits, while waking to meet early morning commitments when required. Sleep irregularity did not predict mental health symptoms in insomnia or DSWPD. Sleep disorder type or symptom severity may have a greater influence on mental health than sleep regularity.