Relationship between depression, smartphone addiction, and sleep among Chinese engineering students during the COVID-19 pandemic

Table 1 Descriptive statistics of depression, smartphone addiction and sleep (n = 692)

Variables	All		Female		Male		Test statistic	P value
	Mean	SD	Mean	SD	Mean	SD
Depression	5.082	4.971	5.425	4.656	4.985	5.056	-0.966	0.335
Smartphone addiction	39.126	11.252	39	10.668	39.161	11.422	0.157	0.876
Pittsburgh Sleep Quality Index	5.496	2.827	5.856	3.023	5.393	2.763	-1.790	0.074
Sleep quality	0.990	0.731	1.059	0.771	0.970	0.718	-1.323	0.186
Sleep latency	0.906	0.858	0.928	0.897	0.900	0.848	-0.360	0.719
Sleep duration	1.009	0.766	1.052	0.768	0.996	0.766	-0.797	0.426
Habitual sleep efficiency	0.201	0.542	0.190	0.483	0.204	0.558	0.293	0.770
Sleep disturbances	0.883	0.574	0.915	0.584	0.874	0.571	-0.784	0.434
Sleep medication	0.104	0.441	0.111	0.467	0.102	0.434	-0.224	0.823
Day dysfunction	1.403	1.007	1.601	1.009	1.347	1.000	-2.771	0.006

Bold represents statistically significant.

Table 2 Correlation analyses among depression, smartphone addiction, and sleep (n = 692)

No.	Variable	1	2	3	4	5	6	7	8	9	10
1	Depression	1.000
2	Smartphone addiction	0.330a	1.000
3	Pittsburgh Sleep Quality Index	0.503a	0.250a	1.000
4	Sleep quality	0.315a	0.153a	0.738a	1.000
5	Sleep latency	0.334a	0.203a	0.676a	0.483a	1.000
6	Sleep duration	0.164a	0.027	0.470a	0.204a	0.072c	1.000
7	Habitual sleep efficiency	0.090b	0.060	0.378a	0.151a	0.156a	0.226a	1.000
8	Sleep disturbances	0.369a	0.182a	0.539a	0.311a	0.351a	0.091b	0.104a	1.000
9	Sleep medication	0.232a	0.036	0.373a	0.219a	0.194a	-0.007	0.076b	0.191a	1.000
10	Daytime dysfunction	0.414a	0.246a	0.664a	0.425a	0.272a	0.179a	0.016	0.210a	0.140a	1.000

^aP < 0.01.

^bP < 0.05.

^cP < 0.10.

Table 3 Multiple linear regression of depression (n = 685)

Variables	Model 1	Model 2	Model 3
Sleep quality	-	-	0.158
Sleep latency	-	-	0.587a
Sleep duration	-	-	0.471b
Habitual sleep efficiency	-	-	0.185
Sleep disturbances	-	-	1.817a
Sleep medication	-	-	1.436a
Daytime dysfunction	-	-	1.304a
Smartphone addiction	-	0.141a	0.082a
Age	-0.130	-0.113	-0.066
Gender	0.526	0.602	0.112
Nationality	-0.524	-0.570	-0.292
Political status	0.435	-0.035	-0.102
Only child	-0.279	-0.047	0.092
Home location	-0.557	-0.668	-0.392
Family socioeconomic status	-0.170	-0.153	-0.181
Father’ education	-0.115	-0.152	0.228
Observations	685	685	685
Adjusted R2	0.011	0.116	0.352

^aP < 0.01.

^bP < 0.05.

^cP < 0.10.

Bold represents statistically significant. Gender: 0 = male, 1 = female. Nationality: 0 = minority nationality, 1 = Han nationality. Political status: 0 = nonparty member, 1 = Communist Party member; only child: 0 = having siblings; 1 = only child. Home location: 0 = rural, 1 = town. Family socioeconomic status: 1 = lower, 2 = lower middle, 3 = middle, 4 = upper middle, 5 = upper. Father’s educational level: 0 = never receiving higher education, 1 = completing higher education.

Table 4 Bootstrapping indirect effect and 95% confidence interval for mediation model (n = 692)

Effect path	Estimated effect	P value	Standard errors	95%CI
Total effects	0.180	0.001	0.025	0.134-0.233
Smartphone addiction-depression	0.104	0.001	0.022	0.063-0.149
Smartphone addiction-sleep latency/sleep; disturbances/daytime dysfunction-depression	0.076	0.001	0.012	0.053-0.102
Smartphone addiction-sleep latency-depression	0.014	0.001	0.005	0.006-0.027
Smartphone addiction-sleep disturbances-depression	0.022	0.000	0.007	0.011-0.040
Smartphone addiction-daytime dysfunction-depression	0.040	0.001	0.009	0.024-0.059

Bold represents statistically significant. 95%CI: 95% confidence interval.