TABLE 2.

Correlations Among Questionnaire Measures and Sleep Variables

	1	2	3	4	5	6	7
Actigraphy
1. Nocturnal duration, hours
2. ln_efficiency	−.38***
3. Average min napped per napping day	−.08	.01
4. Prop. days napped across the full week	−.22**	.01	.31*
Diary
5. Quality	.02	.02	−.03	−.13*
6. Average min napped per napping day	−.15*	.09	.46***	.29***	−.11
7. Prop. days napped across the full week_sqrt	−.18**	.04	.35***	.41***	−.20**	.65***
Questionnaire
8. Sleepiness	−.17***	−.05	.19**	.09	−.11	−.09	.04

Note. Sleep efficiency is reverse scored so that a high score indicates less efficiency. Prop. days napped = proportion of days with at least one nap across the full week. Sleepiness = daytime sleepiness subscale from the School Sleep Habits Survey for Adolescents.

^*p < .05

^**p < .01

^***p < .001.