Table 1.

Descriptive statistics and correlations among variables

	M ± SD	1	2	3	4
1.  Internet addiction	2.06 ± 0.51	–
2.  Poor sleep quality	5.93 ± 2.69	0.34**	–
3.  Rumination	3.22 ± 0.77	0.46**	0.39**	–
4.  Bedtime procrastination	4.17 ± 0.84	0.35**	0.41**	0.30**	–
Age	20.17 ± 1.43	−0.04	0.06*	−0.05	−0.05
Sex	–	0.01	−0.06	0.00	0.06*

Note: *P < 0.05; **P < 0.01. male = 1; female = 0.