Table 4.

Nonparametric correlations: SDI, number of SDI symptoms (0–7), and SQR with sleep and non-sleep variables

	SDI	No. of SDI SX	SQR
Sleep variables
SDI	1.000	0.838^*	−0.277^*
SQR	−0.277^*	−0.184	1.000
NTST	−0.244^†	−0.227^†	0.316^*
DTST	0.114	0.165	−0.282^*
SE	−0.283^*	−0.217^†	0.490^*
WASO	0.243^†	0.175	−0.412^*
DTST/NTST	0.215^†	0.244^†	−0.387^*
24HTST	−0.084	−0.045	−0.007
Non-sleep variables
MMSE	−0.406^*	–	0.192
ADAS	0.459^*	–	−0.161
Hamilton	0.227^†	–	−0.044
NPI	0.341^*	–	−0.074
ADL	−0.451^*	–	0.121

P < 0.05;

^†

P < 0.01.

SQR, sleep quality rating; SDI, Sleep Disorders Inventory; #SDI SX, number of SDI symptoms occurring at least once per week. NTST, night-time total sleep time; DTST, daytime total sleep time; SE: sleep efficiency; WASO, time awake after sleep onset; 24 h TST: DTST + NTST; MMSE, Mini-Mental State Examination; ADAS, Alzheimer’s Disease Assessment Scale; Hamilton, Hamilton Depression Scale; NPI, Neuropsychiatric Inventory (10-item score); ADL, activities of daily living.