Table 7.

Summary of the comparisons with previous studies using other measurements to assess sleep.

Type of feature	Findings in previous studies	Consistenta	Measurement
Insomnia	Insomnia is significantly related to depression [6].	Yes	Questionnaire
Hypersomnia	Prevalence of hypersomnia is high in depressed patients [46].	Yes	Questionnaire
Weekend catch-up sleep	Weekend catch-up sleep is significantly positively correlated with the severity of depression [36].	Yes	Questionnaire
Deep sleep percentage	More deep sleep represents higher sleep quality [32].	Yes	Questionnaire
Awake percentage, Awakenings (>5 mins)	Fewer awakenings after sleep onset represents better sleep quality [32].	Yes	Questionnaire
Sleep efficiency	Higher sleep efficiency represents better sleep quality [32].	Yes	Questionnaire
REM sleep percentage	Increased REM sleep percentage can be biomarkers of depression [9].	No	Polysomnography
REMb latency	Shortened REM latency can be biomarkers of depression [9].	No	Polysomnography

^aWhether it is consistent with our findings.

^bREM: rapid eye movement.