condition mean min max 4 h after light 2.2 2.2 2.2 8 h after light 9.0 8.7 9.3 12 h after light 3.25 3.1 3.4 4 h after dark 2.85 2.1 3.6 8 h after dark 5.2 2.7 7.7 12 h after dark 5.35 2.8 7.9