Table 2.

Ln(cortisol) on waking and waking plus 2.5, 8, and 12 h and bed time (diurnal slope) on recurrent short sleep and chronic insomnia symptoms.

N = 3,064	Recurrent short sleep duration				Chronic insomnia symptoms
	Model 1		Model 2		Model 1		Model 2
	β (SE)	P value	β (SE)	P value	β (SE)	P value	β (SE)	P value
Hours since waking	−0.141 (0.048)	0.004	−0.139 (0.048)	0.004	−0.149 (0.048)	0.002	−0.151 (0.048)	0.002
Hours since waking squared	0.005 (0.002)	0.003	0.005 (0.002)	0.003	0.005 (0.002)	0.001	0.005 (0.002)	0.001
	Recurrent short sleep (frequency)
No occurrences of short sleep	REF		REF
One occurrence	−0.029 (0.035)	0.411	−0.017 (0.036)	0.635
Two occurrences	−0.108 (0.056)	0.052	−0.094 (0.056)	0.088
Three occurrences	−0.190 (0.063)	0.003	−0.163 (0.064)	0.010
	Interaction: hrs since waking × short sleep
No occurrences of short sleep	REF		REF
One occurrence × hours since wakinga	0.009 (0.004)	0.015	0.009 (0.004)	0.015
Two occurrences × hours since wakingb	0.014 (0.006)	0.014	0.014 (0.006)	0.014
Three occurrences × hours since wakingc	0.020 (0.006)	0.002	0.020 (0.006)	0.002
					Chronic insomnia symptoms (frequency)
No occurrences of insomnia symptomsd					REF		REF
One occurrence					0.003 (0.026)	0.912	0.004 (0.026)	0.884
Two occurrences					−0.015 (0.032)	0.628	−0.020 (0.033)	0.548
Three occurrences					−0.052 (0.036)	0.154	−0.060 (0.039)	0.123
					Interaction: hrs since waking × insomnia symptoms
No occurrences of insomnia symptoms					REF		REF
One occurrence × hours since wakinge					−0.001 (0.003)	0.802	−0.001 (0.003)	0.801
Two occurrences × hours since wakingf					−0.003 (0.003)	0.322	−0.003 (0.003)	0.320
Three occurrences × hours since wakingg					0.002 (0.004)	0.553	0.002 (0.004)	0.552

Model 1: recurrent short sleep (frequency) adjusted for cortisol sample number (dummy variables for whether the cortisol came from first/third/fourth/fifth/sixth sample—estimates of these, compared to the first sample are, −0.17, −0.20, −0.66 and −0.98 respectively) + waking time, stress of day of sampling. Model 2: Model 1 + age, sex, employment grade, smoking, alcohol intake, SF-36 Short Form Health Survey (physical and mental component scores), BMI (Body Mass Index), steroids, anti-depressants, sleeping drugs, +other sleep exposure.

^aP = 0.58 for one occurrence of short sleep × hours since waking × sex.

^bP = 0.61 for two occurrences of short sleep × hours since waking × sex.

^cP value = 0.86 three occurrences of short sleep × hours since waking × sex.

^dInsomnia symptoms: defined as number of times, across three time points, participant was in fourth quartile of reported insomnia symptom.

^eP = 0.71 for one occurrence of insomnia symptoms × hours since waking × sex.

^fP = 0.96 for two occurrences of insomnia symptoms × hours since waking × sex.

^gP value = 0.44 three occurrences of insomnia symptoms × hours since waking × sex.