Sleep disorders are, in part, attributable to genetic variability across individuals. There has been considerable progress in understanding the role of genes for some sleep disorders, such as the identification of a human leukocyte antigen gene for narcolepsy. For other sleep disorders, such as insomnia, little work has been done. Optimizing phenotyping strategies is critical, as is the case for sleep apnea, for which intermediate traits such as obesity and craniofacial features may prove to be more tractable for genetic studies. Rapid advances in genotyping and statistical genetics are likely to lead to greater discoveries in the near future.