Table 4.

Correlation coefficients for SSHS sleep variables (columns), environmental factors (rows), and year GPA.

	Pearson correlation coefficients
	Year GPA	Bed time weekdays	Wake up weekdays	TST weekdays	Bed time weekends	Wake up weekends	TST weekends	Weekend sleep lag	Sleepiness	Sleep/wake behavior problems	Depression scale	M/E scale
Year GPA	1.00	−0.39*	0.10	0.43**	−0.51**	−0.11	0.22	−0.16	0.22	−0.10	0.08	0.23
Exercise hours per week	0.41**	−0.22	0.23	0.22	−0.32*	−0.01	0.18	−0.01	−0.11	−0.17	0.01	−0.06
Smoke yes/no	0.14	0.19	0.21	−0.20	0.03	0.08	0.03	0.23	−0.13	−0.16	0.02	−0.26
How many cigarettes smoked per day	−0.15	0.02	−0.26	−0.05	−0.02	−0.10	−0.17	−0.15	0.11	0.13	0.04	0.14
How often alcohol is consumed	−0.08	0.34*	0.00	−0.27	0.10	−0.04	−0.23	−0.02	0.13	0.31	0.04	−0.07
How many units during a drinking session?	0.01	0.11	−0.11	−0.08	−0.12	−0.07	0.08	0.17	0.17	−0.15	−0.08	−0.13
How often energy drinks are consumed	−0.42**	0.56**	−0.04	−0.53**	0.20	0.05	−0.26	0.21	−0.16	0.28	0.04	−0.30
How often coffee is consumed	−0.34*	0.61**	0.12	−0.33*	0.15	−0.07	−0.07	0.23	−0.01	0.01	−0.04	−0.25
Combined caffeinated consumed	−0.45**	0.70**	0.06	−0.48**	0.17	−0.03	−0.21	0.21	−0.09	0.16	−0.01	−0.30
TV weekdays	−0.21	0.34*	−0.10	−0.35*	0.07	−0.13	−0.19	0.11	−0.35*	0.15	0.13	0.01
TV weekends	−0.25	0.26	−0.08	−0.29	0.12	−0.21	−0.21	0.03	−0.25	0.09	0.09	0.13
TV 30 min before bed	−0.44**	0.73**	0.04	−0.54**	0.21	−0.07	−0.16	0.33*	−0.25	−0.07	0.02	−0.28
Social media weekdays	−0.22	0.03	−0.26	−0.19	0.35*	−0.16	−0.23	−0.09	0.06	0.02	−0.07	0.35*
Social media weekends	0.20	−0.16	−0.22	0.04	−0.11	−0.21	0.05	0.02	−0.06	−0.22	−0.21	0.21
Social media 30 min before bed	−0.44**	0.71**	−0.06	−0.52**	0.19	−0.07	−0.19	0.28	−0.17	0.07	−0.09	−0.35*
TV in bedroom	0.02	−0.21	−0.07	0.14	0.13	0.11	−0.04	−0.18	0.04	−0.06	−0.40	0.00

Significant correlations are highlighted in bold with asterisks representing significance levels; ^*p < 0.05, ^**p < 0.01 (1-tailed).