The sleep period was delayed in participants with DSPD
compared to the controls. As shown in Table 2, this includes
later times for lights off, sleep onset, sleep offset and lights
on. Although participants with DSPD spent more time in bed,
TST was not significantly different between the DSPD and
the control group. The higher TWT in the DSPD group was
attributed mainly to longer SOL. Both WASO and EMA were
similar in the two groups. SE was not statistically different
between the groups. Once sleep onset had occurred, no
group differences in sleep architecture were observed. Time
spent in each sleep stage during the sleep period did not
differ between the groups (Table 2). Furthermore, sleep
stage distribution in the first, middle and last third of the sleep
period did not differ between the groups (Table 3). Similar
proportions of SWS were observed in the two groups both
during the first 3 h of sleep