Just came to my attention that there is research of sleep related genes, the usual stuff of protein kinases, dopaminergic receptor, and serotonine transporter. Also this research community seem to have the common difficulty of the complex disease gene mappers – to understand a phenomenon (not a trait) as systemic function, an intrinsic property of a multicellular and multiwired brain, yea, yea.
Addendum
More strange phenotypes orgasm frequency, pain, human memory performance.
Addendum
Read also the what-we-could-have-learned-from-linkage-studies.