what exactly is circadian rhythm?
Harrison: Circadian rhythm is our internal biological clock. It’s tied to cycles of light and darkness and, basically, controls our daily cycles of sleep and activity. Joe: So the first study you said is about a gene that regulates sleep duration or length. Harrison: We all know that different people seem to need different amounts of sleep. These tendencies run in families, suggesting they have a genetic basis. Genes affecting sleep duration had been identified in some organisms, but until now no similar gene had been found in people. In a new study, NIH-supported scientists sequenced the DNA of suspected genes in different families, looking for genetic links to extremely early wake-up times. Joe: And what did they find and how is it significant? They found a mutation in a gene called hDEC2 in a family with two extremely early risers. Family members who carried this mutation slept an average of six and a quarter hours. Noncarriers in the family averaged over eight hours. They all fell
