Figure 2.
Event-free survival Kaplan-Meier curves for four categories by shorter/longer sleep time and riser/non-riser pattern. Log-rank statistic between shorter- vs. longer sleep risers is 6.42 (P=0.03), shorter- vs. longer sleep non-risers 0.07 (P=.79). Log-rank statistic between longer sleep risers vs. longer sleep non-risers was 9.45 (P=0.008), and shorter sleep risers vs. shorter sleep non-risers was 23.8 (P<0.001). Log-rank statistic between shorter sleep risers vs. longer sleep non-risers is 35.0 (P<0.001), and longer sleep risers vs. shorter sleep non-risers is 5.66 (P=0.03).