Delayed sleep-wake phase disorder involves chronic difficulty going to bed and waking up at conventional times and often co-occurs with depression. This study compared sleep and circadian rhythms between patients with delayed sleep-wake phase disorder with depression (DSWPD-D) and without (DSWPD-ND) comorbid depression. Clinical records of 162 patients with delayed sleep-wake phase disorder (70 DSWPD-D, 92 DSWP...