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

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.