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).
3. When the Bedtime is Too Late
What occurs when children are allowed to fall asleep too late at night? They wake up short of sleep in the morning. When you are short on sleep, then, even without caffeine, you get “keyed up” because your body produces stimulating chemicals such as cortisol, adrenaline, and noradrenaline. Then, if you suddenly go on vacation, it takes you a few days to “unwind” or dissipate the effects of the stimulating chemicals. This burst of energy is a primitive biological adaptive response so that early man could fight harder, hunt longer, or flee faster for survival. It’s like a turbo boost that we often call a “second wind”. When present, you are in a state of higher neurological arousal. When the bedtime is too late, he wakes up in the morning in a state of higher neurological arousal which causes him to have difficulty or inability to nap well.
The consequences of not napping well means that by the end of the day his sleep tank is empty and he is in an even higher state of arousal so it becomes more difficult for him to easily fall asleep and stay asleep at night. Parents might not see bedtime battles, long latency to sleep, or night waking resulting from a bedtime that is too late. But of course, he eventually crashes late at night. But this is preceded by an unhealthy state for the child, stressful interactions with him, and stressful interactions as a couple, and stress for each parent as an individual.
Sometimes the naps are very long and late (e.g. 1-4pm) because the bedtime is too late and the child’s sleep deprivation is masked by parents returning home from work and playing with the child.
4. Healthy Sleep is Like Healthy Food
Consider the similarities between food and sleep. Let’s first think about food and food quality. Food is a biological need. Food is energy for the body. Poor quality food –junk food – damages the body by causing all manner of medical issues including malnutrition, anemia, diabetes, heart disease, and obesity. A little junk food is O.K., a lot is not.
Now let’s think about sleep and sleep quality. Quality sleep means consolidated sleep occurring in phase with circadian rhythms. Sleep is also a biological need. Sleep is energy for the brain; poor quality sleep harms the brain. Think of poor quality sleep as junk sleep. Junk sleep is just as bad for our children as junk food. Just as you read labels on food to determine quality, think of sleep quality for your child. You would not starve your child by withholding food; try to not let your child get short on sleep.
Junk sleep causes many problems. All of these points are based on peer-reviewed published research. These are not my opinions.
• Exhaustion, and we all know what that feels like!
• Impaired mood. Children become more irritable, angry, and easily upset; later on, junk sleep can cause or exacerbate depression and marijuana use in adolescents. Less able to regulate emotions.
• Impaired social and academic performance. Kids who are lacking sleep will be more hyperactive, oppositional, and aggressive. Less able to accurately recognize human emotional expressions
• Impaired cognitive development. Sleep incorporates learning into permanent memory, sleep causes memory consolidation, sleep enhances organizational skills, planning, multi-tasking, and executive functioning.
• Impaired personality. Children become fussy, more intense, more frightened, and less adaptable.
• Impaired hand-eye coordination (which impacts a whole host of functions like athletic performance and fine motor skills).
• Systemic inflammation, increased blood pressure, increased stress hormones, increased susceptibility to infections.
•Impaired glucose control which is a factor in diabetes, obesity.
•Maternal depression.
5. Sleep and Brain Development
Never Forget: Sleep Helps the Brain Develop
1. The sleeping brain is not a resting brain.
2. The sleeping brain functions in a different manner than the waking brain.
3. The activity and work of the sleeping brain are purposeful.
4. The process of falling asleep is learned.
5. Providing the growing brain with sufficient sleep is necessary for the ability to concentrate and an easier temperament.
Sleep is the power source that keeps your mind alert and calm. Every night and at every nap, sleep recharges the brain’s battery. Unlike a light bulb that shuts down completely when it is turned off, your child’s sleeping brain is active and purposeful. Providing your child’s growing brain with quality sleep is necessary for its development. Sleeping well increases brainpower just as weightlifting strengthens muscles. Sleeping well makes your child physically relaxed and mentally alert; he is at his personal best. Sleep is not a luxury, sleep is a biological necessity.
6. Updates
From Sleep, 2008-9: “Sleep deprivation-induced performance deterioration is more marked in some individuals than in others. These inter-individual differences in response to sleep deprivation have trait-like characteristics consistent with a genetic basis”, “Sleep problems at 8 years predicted symptoms of depression at 10 years”, “Paternal involvement in infant care may contribute significantly to the development of infant sleep”, “Nap deprivation impacts emotional responses in 2-3year-old children.”
From Science, 2009: “Sleep is important for memory consolidation”, “Sleep is universal, strictly regulated, and necessary for cognition…sleep consolidates memories whereas sleep deprivation interferes with memory acquisition.”
From Pediatrics, 2009: “Sleep problems in childhood predict neuropsychological functioning in adolescents”, “short sleep duration in 7-to 8-year-old children predicts hyperactivity/impulsivity”.
From Proc Natl Acad Sci, 2009: Naps with “REM sleep enhances the integration of unassociated information for creative problem solving…”
From Devel Psychobiol 2010: Children “with more fragmented sleep displayed higher awakening cortisol levels {which} were correlated with {more} internalizing behavior and negative emotionality.”
From Archives of Ped & Adol Med 2010: Short nighttime sleep under age 5 years causes obesity by ages 5-9. “Napping had no effects on the development of obesity and is not a substitute for sufficient nighttime sleep.”
7. Final Thoughts
Sleep is a natural process and there will usually be few difficulties if we are patient and don’t interfere with it. Timing is most important but there are genetically-controlled individual differences between children regarding when their sleep rhythms develop and how long they sleep so don’t compare your child with other children. Naps and night sleep are related and both need to be in place to avoid sleep problems. Our goal is to have well rested families. But always remember, the amount of sleep our children need is measured by mood, behavior, and performance…not hours on a clock. The best advice I can give is: Let your child’s natural sleep rhythms do their job without interference from parents!
