Table 2. Descriptive information for the Pittsburgh Sleep Quality Index (PSQI), Internet Addiction Test (IAT), and their subscales (N = 2749).

Scales or subscales	Mean	SD	Potential range	Actual range	Skewness
PSQI global	6.73	3.16	0–21	0–19	0.43
Subjective sleep quality	1.09	0.81	0–3	0–3	0.46
Sleep latency	0.80	0.88	0–3	0–3	0.17
Sleep duration	0.80	0.88	0–3	0–3	0.17
Sleep efficiency	1.05	1.12	0–3	0–3	0.90
Sleep disturbance	1.14	0.54	0–3	0–3	0.82
Use of sleep medication	0.19	0.55	0–3	0–3	0.29
Daytime dysfunction	1.07	0.82	0–3	0–3	0.36
IAT total	39.65	17.84	0–100	0–100	0.31
Salience	9.10	5.16	0–25	0–25	0.42
Excessive use	10.82	4.96	0–25	0–25	0.25
Neglect work	5.84	3.64	0–15	0–15	0.38
Anticipation	3.68	2.32	0–10	0–10	0.48
Lack of control	7.16	3.63	0–15	0–15	0.15
Neglect social life	3.02	2.08	0–10	0–10	0.64