If you have not already done so, please read Blog Posts 1 through 5 that describe how sleep is important and beneficial. I will post specific information for parents and children based on my book, “Healthy Sleep Habits, Happy Child.” Please do not be put off by my book’s length. This is a reference book. Read only the topic of interest to you.
When the time of falling asleep is too late, a baby becomes overtired. To maintain wakefulness when overtired, the brain produces stimulating chemicals to enhance arousal. But this higher state of arousal makes it harder for baby to subsequently fall asleep and stay asleep at night. This heightened state of arousal in the evening before falling asleep is called ‘pre-sleep arousal’. Pre-sleep arousal causes some fatigue signs, the ‘witching hour’, and a ‘second wind’. In this state of hyperarousal, during the soothing bedtime routine, your baby might fight sleep to maintain wakefulness for the pleasure of parents’ soothing.
In 2008, the first pediatric study, ‘Presleep Arousal and Sleep Disturbances in Children’ among 8-10-year-olds showed that pre-sleep arousal is associated with sleep disturbances in children.
In 2014, a study showed that evening cortisol levels were higher among children 5-12-years-old with insomnia symptoms and shorter sleep durations suggesting physiological hyperarousal in the evening.
In the 2015 fourth edition of my book, the term ‘pre-sleep arousal’ first appears to describe this state:
“The “witching hour” may be thought of as a second wind or pre-sleep arousal state…Pre-sleep arousal was both physical (rapidly beating heart) and cognitive (inability to think)…You also become more prickly or hypersensitive, just as a bad sunburn will make even a light touch painful. This state of hyperarousal is most obvious in a young child in the late afternoon or early evening when his sleep tank is almost empty and he is running on fumes because of missed naps, bedtimes that are too late, or both.”
“At age 3 my first son coined the perfect word to describe this turned–on state: “upcited,” a combination of “upset” and “excited,” as in “Don’t make me upcited!” when we admonished him for behaving like a little monster. Two very interesting Australian studies on adults have helped to shed light on childhood “upcited” behavior. One study showed that the level of activation of the nervous system was associated with certain personality traits, sleep habits, and activity of the adrenal gland. Poor sleepers were more anxious and had higher levels of the hormone cortisol, which typically rises during stressful situations.”
” Concentrations of cortisol also increase with increasing alertness. In children, cortisol concentrations remain high when they do not nap. Perhaps the nap allows the brain to be alert without needing the added boost cortisol provides. Increasing irritability and tenseness—-stress factors—-are also associated with increasing concentrations of adrenaline, noradrenaline, and dopamine. These studies support the notion that when an overly sleepy child appears wired, wild, edgy, excitable, or unable to fall asleep easily or stay asleep, he is this way precisely because of his body’s response to being short of sleep. Think of how you feel when you work hard and lose sleep in order to finish a major project. You are highly motivated and fight the daytime sleepiness. The impairments of performance and discomfort of sleepiness increase. After a while, you feel ‘keyed up’. Thankfully, modern adults are able to get out of this state by taking vacations. But have you noticed how, at the start of a vacation, it takes a few days to ‘unwind’? This is the time required for our accumulated nervous energy to dissipate.”
he 2021 fifth edition of my book included this material and discussed many studies describing how late bedtimes caused both hyper behavior in children in the evening and difficulties in falling asleep and staying asleep at night.
A 2021 landmark paper by Professors Hoyniak, McQuillan, Bates, et. al. ‘Presleep Arousal and Sleep in Early Childhood’ used objective measurements in 54-month-old children to show that pre-sleep arousal was associated with elevated heart rates and more time required to fall asleep after the bedtime routine. (Blog Post 204)
