To investigate the relationship between sleep duration and clock gene polymorphisms, a pair of genetic association studies and a meta-analysis of the two were performed. The first association study was performed in 333 participants from Northern Italy who were recruited from the MICROS study. A second replication study was performed in participants recruited from the Estonian genome project who had very long (>8.5 hours) or very short (<7 hours) sleep durations, as determined by the Munich ChronoType Questionnaire. A meta-analysis of the results from each of the two populations found that the rs12649507 SNP in clock was associated with sleep duration and the rs12649507-rs11932595 GGAA clock haplotype was associated with long sleep duration.
rs12649507-rs11932595 in clock