Table 3.

Ln(cortisol) on waking and after 30 min (morning rise) on recurrent short sleep and chronic insomnia symptoms.

N = 3064	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	0.78 (0.18)	<0.001	0.75 (0.18)	<0.001	0.74 (0.18)	<0.001	0.73 (0.18)	<0.001
Hours since waking squared	−0.77 (0.21)	<0.001	−0.77 (0.21)	<0.001	−0.76 (0.21)	<0.001	−0.76 (0.21)	<0.001
	Recurrent short sleep (frequency)
No occurrences of short sleep
One occurrence	−0.05 (0.04)	0.266	−0.03 (0.05)	0.45
Two occurrences	−0.20 (0.07)	0.003	−0.19 (0.07)	0.007
Three occurrences	−0.26 (0.08)	0.001	−0.22 (0.08)	0.005
	Interaction: hrs since waking × short sleep
No occurrences of short sleep
One occurrence × hours since wakinga	−0.00 (0.11)	0.980	−0.03 (0.11)	0.99
Two occurrences × hours since wakingb	0.45 (0.17)	0.008	0.46 (0.17)	0.008
Three occurrences × hours since wakingc	0.35 (0.20)	0.071	0.33 (0.20)	0.08
					Chronic insomnia symptoms (frequency)
No occurrences of insomnia symptomsd					REF		REF
One occurrence					−0.02 (0.03)	0.485	−0.01 (0.03)	0.668
Two occurrences					−0.03 (0.04)	0.417	−0.01 (0.04)	0.798
Three occurrences					−0.13 (0.04)	0.004	−0.10 (0.05)	0.046
					Interaction: hrs since waking × insomnia symptoms
No occurrences of insomnia symptoms					REF		REF
One occurrence × hours since wakinge					0.10 (0.08)	0.191	0.10 (0.08)	0.194
Two occurrences × hours since wakingf					0.02 (0.10)	0.826	0.02 (0.10)	0.833
Three occurrences × hours since wakingg					0.30 (0.11)	0.007	0.30 (0.11)	0.006

Model 1: adjusted for cortisol sample number (dummy variables for whether the cortisol came from first/second sample—estimates of these, compared to the first sample are, 0.14) + waking time, stress of day of sample. Model 2: Model 1 + age, sex, employment grade, smoking, SF-36 Short Form Health Survey (physical and mental component scores) BMI (Body Mass Index), steroids, anti-depressants, sleeping drugs + other sleep exposure.

^aP = 0.50 for one occurrence of short sleep × hours since waking × sex.

^bP = 0.09 for two occurrences of short sleep × hours since waking × sex.

^cP value = 0.25 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 symptoms.

^eP = 0.64 for one occurrence of insomnia symptoms × hours since waking × sex.

^fP = 0.69 for two occurrences of insomnia symptoms × hours since waking × sex.

^gP value = 0.66 three occurrences of insomnia symptoms × hours since waking × sex.