Blog Post 8-Circadian Rhythms

Healthy Sleep Habits, Happy Child
by Marc Weissbluth, M.D.

A Healthy Child Needs a Healthy Brain,
A Healthy Brain Needs Healthy Sleep.

Sleep is serious business.  If you have not already done so, please read Blog Posts 1 through 5 that describe how sleep is important and beneficial, from the point of view of the United States of America Department of the Army.  A major point, emphasized by the Army, is that more sleep produces more benefits for Soldiers.  Also, more sleep produces more benefits for children.  Even small amounts of extra sleep help (Blog Post 6).  At every age! 

Another point made by the Army is that “Soldiers [Children] best accomplish sleep extension [more sleep] by going to bed earlier.”  The Army is clear about who is in charge: “Planning for sleep is a leader [Parent] competency”

In addition, “Leaders [Parents] also ensure that the sleep-wake schedule conforms as closely as possible to the brain’s natural circadian rhythm to optimize both duration and quality of sleep.  Adequate performance is best achieved by Soldiers [Children] who consistently get adequate sleep on a nighttime sleep-daytime wakefulness schedule aligned with the brain’s natural circadian rhythm of alertness [or Sleep].  Both sleep duration and sleep continuity [Consolidation] are maintained on such schedules.”  Further, “The human brain is biologically hard-wired to be alert during the daylight hours and asleep during the nighttime.  Because of this, poor quality sleep results from night shift work [Late bedtimes or staying up late for schoolwork or social activities] even when the shift worker spends adequate time in bed during the daytime.  Although such a schedule is unnatural for the human brain, some adaptation to a nighttime-awake and daytime-sleep schedule does occur over time, such adaptation is never complete. Soldiers [Children] always pay a cost in their waking performance and daytime sleep quality.”


            An early bedtime may prevent sleep problems from developing in the first place.  Even just a slightly earlier bedtime alone might completely or partially solve a sleep problem (Blog Posts 6 and 7).  An early bedtime might be especially beneficial because it is more aligned with the brain’s natural circadian rhythm. When the sleep period occurs may be as important, or more important, than how long is the sleep duration.


            The brain automatically alternates between wake and sleep outputs.  This is an automatic process over which we have no control.  The ancient and powerful force behind this biological process is the rotation of the earth on its axis creating day and night.  As the earth rotates, dawn occurs.  First, as the sun approaches the horizon, dawn starts with only enough light to cause faint stars to disappear (astronomical dawn).  Second, the sun is close enough to the horizon so that sailors can distinguish the horizon at sea (nautical dawn) but it is still quite dark.  Third, as the sun approaches the horizon, there is enough light to see objects for outdoor activities (civil dawn).  These three phases of dawn are called twilight.  Next occurs sunrise and the start of the day.  At the end of the day, as the sun dips below the horizon at sunset, twilight occurs again.  The process is reversed and the same three phases of dusk occur, followed by night.

Like twilight (not fully day and not fully night), the drowsy state is an in-between state: not fully awake and not fully asleep. Also, like twilight, the drowsy period has a transition with a beginning and an end.  Begin to put your baby to sleep as your baby starts to become drowsy.  The brains in babies and young children also have drowsy periods followed by sleep during the day (naps).  Healthy sleep occurs when the sleep is in synchrony with the occurrence of the brain’s output for sleep both during the day and night.

When you put your well-rested baby to sleep at the beginning of the drowsy period, because the baby’s brain is naturally drifting into a sleep state:

            ·  It is easier for your baby to fall asleep and stay asleep.

            ·  No crying occurs before your child falls asleep.

If your baby is over-tired because of a too late bedtime or naps not occurring in synch with daytime brain outputs for sleep:

            ·  It is difficult for your baby to fall asleep and stay asleep.

            ·  Crying occurs before your child falls asleep.

The sleep solution is to move the bedtime earlier; just a few extra minutes of nighttime sleep makes a big impact (Blog Posts 6 and 7).  And watch for drowsy signs (Blog Post 9) during the day for naps and in the evening for night sleep, which signals you to start soothing your child to sleep for a nap or for the night.



·  Respect your child’s natural sleep rhythms.

・ Encourage an early or earlier bedtime (even a slightly earlier bedtime may produce better sleep. Blog Post 6) especially at 6 weeks. Blog Post 7.

∙ Recognize that a healthy brain requires healthy sleep. Blog Posts 1, 2, 3, 4, and 5.

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