We have genes responsible for our 24-hour body clock. What we have learned just recently is that those genes influence not only the timing of sleep, but also they are responsible for feeling restful in the morning. The recent research study identified changes in the brain that lead to the increased desire and need for sleep during time spent awake. Simply state, for the sensation of sleepiness and fatigue.

Dr. Bruce O’Hara of the University of Kentucky, one of the neuroscientists who conducted the research explained: “We still do not know why we benefit from sleep, or why we feel tire when we are ‘lacking’ sleep, but it seems likely that sleep serves some basic biological function for the brain such as energy restoration for brain cells or memory consolidation.”  Clock gene in the brain is  responsible to analyze sleep debt,  while previous findings have linked these genes to energy metabolism.

To study how gene of clock “knows” sleep debt, three inbred strains of mice with different genetic make-ups were utilized, and which had previously been shown to differ in their response to sleep deprivation by lead author, Dr. Paul Franken of Stanford University and Lausanne University. In this study, mice were first sleep deprived during the daytime period when mice normally sleep then allowed recovery sleep.

Clock gene expression generally increased the more the mice were kept awake and decreased when sleep was allowed, supporting that these genes play a role in the regulation of the need for sleep. The changes in gene expression were also shown to occur in many different brain regions supporting the idea that sleep is a global brain function.

A handful of genes such as  it have been shown previously regulate our circadian rhythms (behavior and physiology that follow a 24 hour cycle). The major advantage of circadian rhythms is that they allow animals and plants to predict and prepare for periodic changes in the environment. The anticipatory increase in clock-gene expression may be, on a molecular level, an animal’s preparation for activity.

Variations in clock genes may explain why we are different in our sleep – wake rhythm, our preferred wake-up time, but also our sleep duration needed for adequate performance during awake. The research could also help to understand the biology of mood disorders, such as Seasonal Affective disorder (SAD) or bipolar disorder, that link to both sleep and circadian rhythms.

Reference: Sleep Diagnosis and Therapy
Vol 2 6 December 2007