How Much Sleep Do We Need and the Regulation of Sleep

(Adapted from Science: 325:825, 2009)

Sleep and Wakefulness are controlled by two interacting processes which are each independently regulated and under genetic control. It's messy and complex but I will try to give you an overview so that you better understand why you should never compare children. The bottom line is that sleep, like height and weight, is highly inherited.

1. Circadian Process

This sets the timing of sleep onset and offset. The biologic times of drowsiness and awakening are controlled by this internal clock.

There are individual differences among adults and children.

2. Homeostatic Process

This tracks sleep need and forms the genetic basis for how long we sleep (sleep need). If we get shorter and shorter on sleep, we feel more pressure (drowsiness, sleepiness) to get sleep. It's like feeling more and more thirsty as we become more dehydrated. But there is a catch. Sleep loss is primarily recovered by increasing sleep intensity (deep or slow wave sleep) and not necessarily by sleep duration. Maybe shorter periods of intense sleep can be more restorative than longer periods of light sleep or fragmented sleep. That's why sleep quality (intensity, consolidation, and in phase with circadian rhythms) is more important than just sleep duration.

There are individual differences among adults and children.

The developmental pace of these two processes is not the same in all children as any parent of fraternal twins knows! So don't compare children and be PATIENT. Some children will sleep longer and easier than others at any given age.

Our goal is to have well rested families. But, always remember, the amount of sleep we need and the amount of sleep our children need is measured by mood, behavior, and performance…not hours by a clock.

Marc

Filed under: Healthy Sleep