Is sleeping enough really enough?
How many times have we heard sleep experts say that children should get more sleep? That’s pretty simple, right? But what does “more” mean? And is that all there is to it? Getting enough sleep is essential for optimal functioning, and guidelines for how long a child should be sleeping per night have been established by professional sleep organizations. For example, guidelines of the American Academy of Sleep Medicine state that a 6- to 12-year-old child should, on average, sleep between 9 and 12 hours every 24 hours.
But sleeping long enough is only part of the story. The quality of one’s sleep is another important aspect of sleep. Even if time in bed allows for enough hours, one must sleep well to reap the benefits. Sleeping well means falling asleep within a relatively short time after going to bed and sleeping with few or no waking periods during the night. While sleep duration has an easy way of measuring everyone agrees upon, hours, there is no such easy determination for quality of sleep. When someone is asked “How did you sleep?” the usual response is some variation of “well” or “not well.” Sleep researchers have ways of measuring sleep quality, including the exact time between bedtime and falling asleep, minutes of waking periods during the night, movement during sleep, and sleep disruptions such as nightmares and breathing problems. Surveys are also used to ask individuals about their sleep quality.
It is less well known that sleep regularity is of equal importance as duration and quality. Going to sleep and waking up at about the same times every day has been found by researchers to afford health benefits, and when schedules are irregular, problems may arise. One common cause of irregularity for school age children is going to sleep and waking up later on weekends than on school days. Because school begins at the same time during the week, most children wake up at about the same time. Bedtimes are usually set by parents based on the child’s age and the amount of sleep a child is thought to need to be fully rested, and those tend to be about the same time every night. Weekend sleep schedules are commonly different, with later bedtimes and wake times. In other instances, sleep schedules may be irregular during the school week for various reasons such as parents not setting regular bedtimes, sleeping at places other than home, or being allowed to stay up later occasionally under special circumstances.
Many studies have found that Irregular sleep schedules are related to health problems. For example, Karen Spruyt and colleagues (2011) studied relations between sleep duration and regularity and body mass index in a sample of young children and discovered that while children slept about the same number of hours regardless of their weight, overweight and obese children’s sleep schedules were more variable. Irregular schedules were associated with metabolic problems including altered levels of insulin, low density lipoproteins and C-Reactive proteins. In a study of 120,000 adults over two years, irregular sleep was related to increased obesity and its associated health risks (Jaiswal et al., 2020).
Why does an irregular sleep schedule lead to these problems? Research on circadian rhythms has shown that metabolic processes occur at timed intervals throughout the 24-hour day. When the timing of those processes is disrupted, health risks increase. Timing of metabolic processes is controlled by clock mechanisms in both the central areas of the brain and in peripheral areas throughout the body. Most of us are familiar with how eating “off-time” can result in dysregulation of the digestive system. In a similar fashion, sleeping at irregular times can be disruptive to multiple body processes.
So how does this translate to how parents manage their children’s sleep? The best practice is to aim for bedtimes as constant as possible whether on a school night or a weekend. If you want the full benefits of sleep, just sleeping more is not enough unless that sleep is regularly timed.
