Table 1.

Socio-demographic and smartphone use characteristics of college students and comparison between poor sleepers and normal sleepers by variable.

Variable		No.	Poor sleepers	Normal sleepers	χ2	P
Gender	Male	58	10	48
	Female	381	33	348	4.194	0.041
Age	≤19 years	274	22	252
	≥20 years	165	21	144	5.573	0.109
Place of origin	Rural	246	27	219
	Urban	193	16	177	0.883	0.347
Self-rated family economic status	Good	26	3	23
	Fair	256	21	235
	Poor	157	19	138	1.984#	0.364
Subjective social support*	≤9	227	25	202
	>9	212	18	194	0.790	0.374
Utilization of social support*	≤8	288	32	256
	>8	151	11	140	1.641	0.200
Depressive symptoms*	≤2	220	13	207
	>2	219	30	189	7.537	0.006
Good physical health	Yes	381	31	350
	No	58	12	46	8.978	0.003
Headaches	Yes	92	18	74
	No	347	25	322	12.575	<0.001
Characteristics of phone use
Years of smartphone use*	≤4	267	17	250
	>4	172	26	146	9.063	0.003
Monthly smartphone charge (Yuan)*	≤50	236	17	219
	>50	203	26	177	3.880	0.049
Hours of daily smartphone use*	≤5	249	16	233
	>5	190	27	163	7.392	0.007
Hours of daily mobile internet use*	≤5	260	12	248
	>5	179	31	148	19.362	< 0.001
Mobile phone addiction index
Inability to control cravings*	≤14	239	15	224
	>14	200	28	172	7.352	0.007
Feeling anxious and lost*	≤7	258	18	240
	>7	181	25	156	5.625	0.018
Withdrawal or escapism*	≤7	259	25	234
	>7	180	18	162	0.015	0.904
Productivity loss*	≤5	231	13	218
	>5	208	30	178	9.583	0.002

*All continuous variables were dichotomized at the median value.

^#Fisher's exact test.