Table 2.

Personally optimal time of day by self-assessed chronotype: OLS regression analysis.

PANEL 1: MORNING HOURS
	7 a.m.	8 a.m.	9 a.m.	10 a.m.	11 a.m.	12 noon
Chronotype	(1)	(2)	(3)	(4)	(5)	(6)
Definitely evening	−37.22***	−46.17***	−53.34***	−39.65***	−27.66***	−15.63**
Evening	−34.18***	−38.02***	−44.38***	−29.54***	−22.58***	−10.11*
Mixed	−12.70*	−24.61***	−28.57***	−21.34***	−17.12***	−8.232
Intercept: Morning	47.22***	63.02***	82.14***	86.46***	86.17***	80.85***
R-sq	0.295	0.316	0.421	0.262	0.173	0.052
N	178	182	184	185	182	182
PANEL 2: AFTERNOON HOURS
	1 p.m.	2 p.m.	3 p.m.	4 p.m.	5 p.m.	6 p.m.
Definitely evening	−5.508	6.383	4.251	2.979	7.376	11.73*
Evening	−2.660	2.660	4.972	6.383	10.11*	10.11*
Mixed	−0.482	5.220	9.291	7.979	5.471	8.853
Intercept: Morning	76.06***	68.62***	66.30***	67.02***	65.96***	64.36***
R-sq	0.008	0.011	0.017	0.015	0.024	0.039
N	182	183	180	182	181	182
PANEL 3: EVENING HOURS
	7 p.m.	8 p.m.	9 p.m.	10 p.m.	11 p.m.	12 midnight
Definitely evening	15.56***	23.88***	24.70***	29.89***	30.21***	33.50***
Evening	11.17*	14.89***	12.77**	12.15*	16.18**	9.944
Mixed	6.066	9.195*	10.78*	11.67*	16.87**	12.51*
Intercept: Morning	65.96***	62.23***	61.17***	53.80***	39.67***	32.61***
R-sq	0.066	0.146	0.134	0.149	0.128	0.164
N	182	181	181	181	179	179

Optimality is measured by a series of questions “At what time of day do you feel at your best?” asked for each hour of the day and scored: definitely yes = 100; yes = 75; Mixed, undecided = 50; no = 25; and definitely no = 0. Metric regression coefficients.

^*p < 0.05,

^**p < 0.01,

^***p < 0.001.

US university students about equally divided into morning (the reference group), mixed, evening, and “definitely evening” chronotypes.