Sleep duration and breast cancer: a prospective cohort study
Cancer Res. 2005 Oct 15;65(20):9595-600.
Verkasalo PK, Lillberg K, Stevens RG, Hublin C, Partinen M, Koskenvuo M, Kaprio J.
Inverse association between sleep duration and breast cancer risk, possibly due to greater overall melatonin production in longer sleepers.
Hazard ratios (HR) in sleepiness.