Much has been learned over the last two decades about the basic biology of sleep/circadian rhythm. We know the mechanisms as to how the clock keeps time and that clocks are in all organs, controlling the daily rhythm of the organ’s function. Light plays a critical role and we know the mechanism by which light/dark cycles entrain the molecular clock.

The functions of sleep at a fundamental molecular level are also being elucidated. This has been facilitated by the identification of sleep states from worms (C. elegans) to fruit flies (Drosophila) to mammals.

These basic biological findings are underpinning a growing interest in the relevance of sleep loss. We know that most aspects of sleep—sleep duration, timing of the major sleep bout, response to sleep loss—have major genetic determinants. Relevant genes are being identified.

Chronic sleep insufficiency is getting increasingly common in our society and adversely affects some components of our population such as youth, shift-workers, etc. The consequences of sleep loss can be devastating leading to major accidents. The effects of sleep loss are, however, not only on performance but also on metabolism, including impaired glucose handling.

In addition to sleep insufficiency, there is a growing recognition of how common in the population sleep disorders such as insomnia, sleep apnea, restless legs syndrome, are. Sleep health is becoming one of the pillars of health and new strategies are emerging to deal with these common problems