Table 2.

Pittsburgh Sleep Quality Index (PSQI) inter-component Spearman’s correlations and descriptive statistics for each timepoint.

		1	2	3	4	5	6	7	8
Timepoint 1	1. Subjective sleep quality	1
	2. Sleep latency	0.42 **	1
	3. Sleep duration	0.29 **	0.22 **	1
	4. Habitual sleep efficiency	0.09 *	0.15 **	0.36 **	1
	5. Sleep disturbances	0.27 **	0.36 **	0.10 *	0.10 *	1
	6. Sleep medication use	0.09 *	0.07	0.08	0.06	0.08	1
	7. Daytime dysfunction	0.32 **	0.25 **	0.20 **	0.04	0.31 **	0.14 **	1
	8. Global PSQI	0.60 **	0.65 **	0.67 **	0.57 **	0.49 **	0.27 **	0.53 **	1
	Mean	1.04	0.94	1.03	0.61	1.10	0.07	0.69	5.48
	Standard deviation	0.55	0.85	0.93	0.98	0.51	0.37	0.66	2.76
	Median	1	1	1	0	1	0	1	5
	IQR	1–1	0–1	0–2	0–1	1–1	0–0	0–1	4–7
Timepoint 2	1. Subjective sleep quality	1
	2. Sleep latency	0.39 **	1
	3. Sleep duration	0.21 **	0.21 **	1
	4. Habitual sleep efficiency	0.12 *	0.23 **	0.29 **	1
	5. Sleep disturbances	0.26 **	0.40 **	0.09	0.15 **	1
	6. Sleep medication use	0.14 **	0.09 *	0.01	−0.01	0.13 **	1
	7. Daytime dysfunction	0.34 **	0.21 **	0.16 **	0.02	0.28 **	0.22 **	1
	8. Global PSQI	0.58 **	0.67 **	0.60 **	0.60 **	0.54 **	0.29 **	0.53 **	1
	Mean	0.98	0.90	0.95	0.70	1.09	0.09	0.72	5.41
	Standard deviation	0.52	0.82	0.91	1.03	0.55	0.42	0.70	2.79
	Median	1	1	1	0	1	0	1	5
	IQR	1–1	0–1	0–2	0–1	1–1	0–0	0–1	3–7
Timepoint 3	1. Subjective sleep quality	1
	2. Sleep latency	0.45 **	1
	3. Sleep duration	0.32 **	0.29 **	1
	4. Habitual sleep efficiency	0.19 **	0.18 **	0.26 **	1
	5. Sleep disturbances	0.27 **	0.31 **	0.17 **	0.08	1
	6. Sleep medication use	0.01	0.13 *	−0.01	0.01	0.11 *	1
	7. Daytime dysfunction	0.41 **	0.24 **	0.19 **	0.06	0.26 **	0.09	1
	8. Global PSQI	0.67 **	0.70 **	0.65 **	0.50 **	0.52 **	0.24 **	0.55 **	1
	Mean	1.01	0.86	0.97	0.42	1.08	0.09	0.64	5.08
	Standard deviation	0.58	0.87	0.94	0.80	0.55	0.42	0.67	2.77
	Median	1	1	1	0	1	0	1	5
	IQR	1–1	0–1	0–2	0–1	1–1	0–0	0–1	3–7

* p < 0.05; ** p < 0.01; IQR: inter-quartile range; PSQI; Pittsburgh Sleep Quality Index.