Table 2

Color dimensions (mean ± SD) for subjects with blue and brown irises.

Iris Color

Blue Irises

Brown Irises

Correlation with

Dimension

n = 7

n = 6

phase shift (n = 13)^b

Blue^a

125.5 ± 9.6**

42.7 ± 9.3

r = .40, p = 0.17

Green^a

143.0 ± 5.2**

93.3 ± 18.0

r = .31, p = 0.31

Red^a

130.1 ± 2.2

123.0 ± 17.3

r = .14, p = 0.64

Lightness

57.9 ± 1.4*

43.0 ± 7.2

r = .29, p = 0.33

* p < 0.01; ** p < 0.001, t-test comparing subjects with blue vs brown irises

^a Measured from 3 dimensions of the RGB color system.

^b Positive correlations indicate that subjects with darker irises had larger phase delays.

Canton et al. Journal of Circadian Rhythms 2009 7:8   doi:10.1186/1740-3391-7-8