This Harvard sleep summary page [0] gives a few references at the bottom for similar sounding studies. [0] http://healthysleep.med.harvard.edu/healthy/science/

This Harvard sleep summary page [0] gives a few references at the bottom for similar sounding studies. [0] http://healthysleep.med.harvard.edu/healthy/science/variations/individual-variation-genetics http://healthysleep.med.harvard.edu/healthy/science/variatio...