This chapter focuses on advances towards heritability and genetic approaches in insomnia disorders in human. Insomnia remains a heterogeneous condition that is primarily characterized and diagnosed by subjective complaints about dissatisfaction with sleep quantity or quality, and it is not associated with any specific biomarker. Some of the first twin studies with a focus on insomnia suggest the involvement of genetic factors in early-onset (childhood) insomnia. The first familial study on insomnia using a clinic based sample suggests the presence of familial insomnia aggregations, especially among individuals with childhood or adolescence onset compared to those with adult onset. Twin studies strongly suggest that genetic factors may trigger insomnia with genetic effects accounting for approximately one-third of the variance in insomnia complaints. Results from twin studies suggest that heritability would potentially account for large proportion of variance in insomniac symptoms.