Table 2.

Results of linear regression models with work day midsleep timing as the dependent variable.

Model	Independents	β	p
1	Mensa	0.096	0.009
2	Mensa	0.036	0.204
	Work start time	0.626	<0.001
	Commute duration	−0.150	<0.001
3	Mensa	0.044	0.116
	Work start time	0.630	<0.001
	Commute duration	−0.143	<0.001
	Cigarettes/day	0.094	0.002
	Beer/day	−0.010	0.732
	Glass wine/day	−0.023	0.426
	Liquor/day	0.032	0.252
	Coffee/day	0.014	0.624
	Caffeine drink/day	0.071	0.014
	Tea/day	−0.023	0.404
	Hypnotics/day	0.023	0.403

Positive standardized regression coefficients for “Mensa” indicate later midsleep timing in Mensa members. Model 3 incorporates the self-reported number of various alcoholic beverages, coffee and other caffeinated beverages, cigarettes and hypnotics medication consumed on a typical day.