Table 1: Subject Demographics.

From: Circadian rhythms of European and African-Americans after a large delay of sleep as in jet lag and night work

 African AmericanEuropean American
N2322
Sex10 Men 13 Women12 Men 10 Women
Age Range21 to 4418 to 41
Age (Mean ± SD)32 ± 7.129 ± 6.5
MSFa (Mean ± SD)4.8 ± 1.25.2 ± 1.1
MEQb
 Score (Mean ± SD)56.5 ± 8.551.3 ± 8.8*
 # of M-Types125
 # of N-Types1015
 # of E-Types12
 BMI (kg/m2) (Mean ± SD)25.0 ± 3.923.5 ± 3.4
Genetic Ancestryc (Mean ± SD)
 % European13.1 ± 9.986.1 ± 9.7
 % Sub-Saharan African78.7 ± 10.35.9 ± 7.6
 % East Asian3.4 ± 6.13.6 ± 5.5
 % Indigenous American4.7 ± 6.54.2 ± 6.0
  1. *Significant difference between African-Americans and European-Americans (p < 0.05 by 2-tailed t-test). Higher scores indicate more morningness.
  2. There were no differences between African-Americans and European-Americans in age, MSF or BMI.
  3. aMid Sleep on Free Days from Munich Circadian Type Questionnaire (MCTQ).
  4. bMorningness-Eveningness Questionnaire (MEQ) score and number of Morning, Neither and Evening Types.
  5. cBiogeographical ancestry estimates based on ancestry informative markers.