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: “Individuals who maintain consistent sleep-wake schedules derive maximum benefits from the circadian rhythm of alertness, with well-consolidated sleep at night and optimum alertness during the daytime.” And: “When mission requirements [Specific family circumstances and specific events] do not allow for adequate sleep, the goal becomes twofold: to optimize alertness and performance during the waking periods to the extent possible and to maximize the ability of Soldiers [Children] to take advantage of any opportunities that do occur.” And: “Although the circadian rhythm of alertness generally promotes a 24-hour cycle of daytime wakefulness and nighttime sleep, there is also a temporary afternoon “dip” in alertness. Soldiers [Young children] can generally take afternoon naps.”
When you consider healthy and high-quality food for your child, you think about different elements such as protein, fat, sugar, carbohydrates, salt, vitamins, and minerals. Food quantity, calories consumed, is important, but that’s not the whole story. Too much low-quality food, junk food, is unhealthy.
When you consider healthy and high-quality sleep for your child, you think about different elements such as naps, sleep consolidation, sleep schedule or timing of sleep, and sleep regularity. Sleep quantity, hours asleep, is important, but that’s not the whole story. Too much low-quality sleep, junk sleep, is unhealthy (Blog Posts 1 though 12).
Naps are not little bits of night sleep randomly intruding upon children’s waking hours. Naps have their own rhythms and purposes. Our mental state fluctuates during the day between alert and drowsy, just as fluctuations occur during the night between light and deep sleep stages (Blog Post 8). Experimentally, in toddlers at 30-36 months, when only one nap is eliminated, Dr. Rebecca Berger observed “dampened positive emotion displays when positive responses are expected [children solve a solvable puzzle] as well as increased negative emotions when negative emotions are expected [children are presented with an unsolvable puzzle].” Specifically, when nap restricted, they showed less joy and pride and more worry and anxiety in the two situations.
Naps are different from night sleep and long naps do not fully compensate for short night sleep. Also, not every nap is created equal.
Let’s protect opportunities for naps and early bedtimes in our children so they can get all the REM sleep they need!
Sleep inertia explains why some adults avoid naps and some children cry when the nap or night sleep ends. Sleep inertia is a feeling of disorientation, confusion, pain, discomfort, impaired mood, and the inability to concentrate or think well that occurs upon awakening. In children, sleep inertia appears to be more severe and more prolonged among those who are more overtired. If your child awakens with crying from sleep inertia, consider your child to be short on sleep. During sleep inertia, it appears that sleep is intruding into wakefulness and this overlap state is painfully uncomfortable. In other words, we are partially awake and partially asleep at the same time. The fact that part of the brain can be asleep while other parts are awake, at the same time, might explain sleep inertia and local sleep.
Local groups of nerve cells in a tiny area of the brain might go offline-that is, go to sleep for a very short nap when you think that you are fully awake. Local regulation of sleep and wakefulness can exist simultaneously in different regions of the brain. In addition to regional anatomical variability of asleep or awake, there are also gradations of regional variability. In other words, different areas of the brain are not just asleep or awake like a light switch being on or off, but instead, the electrical activity reflecting sleepiness is a graded or continuous variable, like a dimmer switch. Thus, for any specific region of the brain, at different times during the sleep-wake cycle, there is variable electrical activity on a continuum between sleepiness and wakefulness. Local sleep is more likely when we are short on sleep.
Recent research tells us that the purpose of sleep is to weaken or prune the unimportant noise coming into our brain so that important signals remain stronger. During sleep the brain is refreshed by eliminating memories of insignificant events, but memories of more important or salient items will be preserved. This culling of information allows for more memory resources to be available the next day. It appears that only during REM sleep, certain nerve cells start firing the electrical signals necessary to remove unimportant memories. Experimental sleep restriction primarily leads to deficits of REM sleep, so that maybe the brain gets cluttered with unimportant memories and makes it harder for us to focus on the present. The more a portion of the brain is used in a task, the more likely it is that this particular area might need to shut down to take a break and do some pruning, leading to local sleep. Local sleep is a by-product of a local increase in learning and is more likely when we are short on sleep.
The point where you are not drowsy from insufficient sleep and you are not up so long that local sleep takes place may be described as optimal wakefulness or optimal alertness. The importance of optimal wakefulness for Soldiers (see above) and children cannot be overemphasized. Sleep is the power source that keeps your mind alert and calm. Sleep recharges the brain’s battery.
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