This result suggests for the first time that sleep need is under strong genetic control, and genes can

be identified underlying sleep homeostasis. Conclusions The functions of sleep remain elusive. Understanding the regulation of sleep at the molecular level represents a powerful step to gaining access to the enigma of sleep. Although evidence has accumulated to indicate a major role for genetic factors in normal and pathological sleep, the underlying molecular mechanisms have not been elucidated, except in a few rare sleep disorders. Like most other complex traits, sleep is controlled by many genetic and environmental factors. Inhibitors,research,lifescience,medical New strategies are becoming available for genetic dissection of complex phenotypes. Inhibitors,research,lifescience,medical The hope of finding single genes that determine the presence or absence of any vigilance states in an all-or-nothing manner is highly unrealistic. However, as reviewed here, sleep-related endophenotypes, such as the sleep EEG features, can be controlled by single or major genes. A noteworthy discovery is that such genes indicate unpredicted pathways (eg, β-oxidation and vitamin A signaling) that are not only implicated in sleep but link sleep to other complex Inhibitors,research,lifescience,medical behaviors. Selected abbreviations and acronyms EEG

electroencephalogram LTP long-term potentiation NREM non-rapid eye movement QTL quantitative trait loci REM rapid eye movement SCN suprachiasmatic nucleus TPF theta peak frequency Notes This work was supported by the State of Vaud and the Swiss National Inhibitors,research,lifescience,medical Science Foundation.
Biologlcal clocks are devices that can measure time In the absence of environmental timing cues, such as changes In light Intensity, temperature, or humidity.1 The discovery of circadian clocks dates back to 1729, when the French astronomer Jean Jacques Ortous de Malran observed that mimosa plants continued to open and close their Inhibitors,research,lifescience,medical leaves in a daily manner when kept in the absence of sunlight.2 Selleck AZD6244 Obviously, other environmental

oscillations such as daily temperature fluctuations could have driven the cyclic leaf openings in de Mairan’s experiment, thereby challenging his conclusion about the existence of a mimosa clock. However, in 1832 the Swiss physician and botanist Augustin Pyrame de Candolle heptaminol demonstrated that in constant light mimosa plants opened and closed their leaves with a cycle of 22 hours rather than 24 hours.3 This observation provided irrefutable evidence that the leaf movement rhythm was not merely driven by cyclic environmental cues depending on the earth’s rotation, but by a self-sustained biological clock. Incidentally, “circadian” is derived from the Latin words “circa diem” and indicates that circadian clocks can measure days only approximately. Hence, the phase of circadian oscillators must be corrected daily to stay in resonance with geophysical time. The photoperiod (ie, daily variations in light intensity) is the primary Zeitgeber for the synchronization of circadian clocks.