1. The single most important fact to remember is that the time when sleep occurs is more important than the duration of the sleep period. You can’t fight circadian rhythms! We all have internal clocks that are genetically controlled. These clocks create an internal timing mechanism for sleep. These clocks evolved from dark (night)/light (day) cues. This signal is very primitive because it is based on the rotation of the earth on its axis. Sleeping in synch with circadian rhythms is more restorative, of better quality, than sleeping out of synch with circadian rhythms. Jet-lag syndrome is an example of sleep not in synch with circadian rhythms.
Additionally, a bout of sleep that is continuous (consolidated) is much more restorative than a bout of sleep that in interrupted (fragmented).
2. The Myth of Total Sleep Duration
Some parents observe that their child is getting 12 hours of sleep (e.g. 9pm to 7am plus a 2 hour nap) and therefore they think that there is no problem. Sleep duration is probably less important than sleep quality (intensity, consolidated, and in phase with circadian rhythms).
