But "the details in the process are really completely unknown," says Fu.
In 2001, the team discovered a mutated gene that caused some members of several families to be "morning larks," awaking around 3:30 a.m. and going to bed around 7:30 p.m. The condition, which the researchers named "familial advanced sleep phase syndrome," is believed to be primarily a variant, or mutated, form of a gene involved in regulating circadian rhythms. The total daily sleep time in people with this condition is normal.
In the current study, the team identified a small extended family in which a mother and her adult daughter had life-long shorter daily sleep requirements than most individuals. Fu's lab then studied blood samples from these women and their extended family. They identified a mutation in a gene known as hDEC2, which is a transcription factor that represses expression of certain other genes and is implicated in the regulation of circadian rhythms.
Next, the team genetically engineered mice and fruit flies to express the mutated human gene, and Ying He, PhD, a postdoctoral fellow in the Fu lab, studied its impact on their behavior and sleep patterns. Mice slept less, as seen in the extent of their scampering about in the dark (mouse preference) over the course of 24 hours and in electroencephalography (EEG) and electromyography (EMG) measurements indicating reduced nonREM and REM sleep. While lacking a Lilliputian size EEG to monitor the fruit flies, He
|Contact: Jennifer O'Brien|
University of California - San Francisco