Author Interviews, Sleep Disorders / 27.03.2013 Interview with: Christer Hublin Apulaisylilääkäri, neurologian dosentti (Helsingin yliopisto) - Assistant Chief Medical Officer, Docent (Adjunct Professor) in Neurology (Helsinki University) Unilääketieteen erityispätevyys (Suomen lääkäriliitto) Sleep medicine specialist (NOSMAC/ESRS) Työterveyslaitos - Finnish Institute of Occupational Health FIN-00250 Helsinki Finland What are the main findings of the study? Answer: We found in an adult twin cohort (the Finnish Twin Cohort) that the proportion of variance in sleep length accounted for by genetic effects was relatively low (about one third) but stable (correlation 0.76 over a period of 15 years.). In contrast, the proportion of variance accounted for by environmental effects was high (about 0.7) and these effects were less stable (correlation over the time period 0.18). The proportion of short sleepers was more than doubled in both genders, whereas in the proportion of long sleepers no major change was seen during the follow-up. To our knowledge, this is the first longitudinal study providing data on the contribution of genetic factors to stability and change of sleep length over time. (more…)