Table 3: Factor loadings of 34 Sleep Questionnaire and Sleep Symptom Checklist items.

Daytime difficultySleep initiation problemSleep maintenance problemPsychological distressSleep apnea symptomsNon-refreshed in morning

Sleepy during the day? (10 = very) .877
Tired during the day? (10 = very).821
Daytime sleepiness (3 = very severe).807
Daytime fatigue (3 = very severe).739
Falling asleep during the day when not wanted (3 = very severe).652
Naps, days/wk..576
Difficult to concentrate? (10 = very) .557
Trouble falling asleep (3 = very severe).774
Insomnia distress (10 = very) .729
Insomnia (3 = very severe).726
Do you have insomnia? (yes/no)−.708
Tension when falling asleep (100 = very tense).696
SOL (hrs.).618
WASO (hrs.).790
TST (hrs.)−.723
Waking up and trouble getting back to sleep (3 = very severe).689
Waking up too early in the morning (3 = very severe).576
Depression (3 = very severe).781
Poor emotional well-being (3 = very severe).781
Anxiety (3 = very severe).710
Interruption of breathing during sleep (3 = very severe).853
Snoring (3 = very severe).767
Waking with a dry mouth (3 = very severe).587
Refreshed in the morning (10 = very refreshed)n/a
Sleep is non-refreshing (3 = very severe)n/a