I will share with you 4 unpublished findings that emphasize the importance of early bedtimes. I asked the authors of 4 different published studies to reanalyze their data and now I will share with you their findings.
- Published studies have shown that the more often that a bedtime routine is practiced, the longer the child sleeps at night. This means that mothers who practiced a bedtime routine 1-2, or 3-4 or 5-6 or 7 times per week had progressively longer night sleep durations. However, I asked the authors whether longer night sleep durations were more associated with frequent bedtime routines or early bedtimes. Answer: “the biggest driver of nighttime sleep is what time a child goes to sleep.”
- Published studies have shown that the more consistent a bedtime routine is practiced, the longer the child sleeps at night. This means that mothers who followed the same sequence of events for a bedtime routine had children who slept longer at night. I asked the authors whether longer night sleep durations were more associated with consistent bedtime routines or early bedtimes. Answer: “Early bedtime is a more direct and stronger predictor of longer concurrent sleep durations from 3 to 24 months, above and beyond bedtime routine”
- Published studies have shown that maternal sleep-related cognitive biases about whether the night waking child is or is not going to feel abandoned or neglected at night, if unattended, affects sleep durations. I asked the authors whether longer night sleep durations were more associated with maternal sleep-related cognitions or early bedtimes. Answer: “Early bedtime is more strongly correlated with long sleep durations than maternal cognitions.”
- Published studies have shown sleep quality was worse in infants with slow development of sleep-wake rhythms. At 3 and 8 months, infants in the ‘Slow sleep-wake rhythm development’ group had longer naps, more difficulties in settling to sleep, longer times required to fall asleep (sleep-onset latency), shorter night sleep, and bedtimes that were about one hour later than the comparison group. Nowhere in the paper did the authors discuss the possibility that instead of a within-the-child problem called ‘slow sleep-wake rhythm development’, the actual problem was that the parents were putting their child to bed too late. In fact, in their discussion, the bedtime was not mentioned. I asked an author whether the sleep problems might be due to a parent-created late bedtime instead of a biological development delay within the child. Answer: It is true that when we examined the circadian rhythm development in this paper, we did not examine the effect that the bedtime had on this circadian rhythm development and/or control for bedtime. If the parents put their children late to bed, this would of course affect the sleep duration, and consequently our measure of circadian rhythm development.
I asked the author (item 4): Please correct me if I am wrong, but I think all of your results could occur from a parent putting her child to bed too late. Late bedtimes are associated with increased latency to sleep, more night wakings, longer night wakings, (more Wake After Sleep Onset), less night and total sleep duration, plus sleep problems such as bedtime resistance and signaled night awakenings. If true, then slow maturation of sleep-wake circadian rhythms is not the problem. In addition, the good news is that there is a simple message to parents: move the bedtime earlier!
The author’s response: Yes, I totally agree with you! And I think this is one of the main “problems” in the sleep research in early childhood. Most of the child sleep patterns are directly dependent on the parents at these early stages, and as you mention here, the time the parents decide to put their child to sleep, might affect most of the sleep-wake patterns. We found that maternal eveningness was associated with most of the sleep problems in early childhood (Blog Post 70). And this makes a lot of sense; in our case, when Vera was born and I started noticing the relevance of early bedtime (and especially after having the discussions with you) my husband and I had first to change our schedules and start doing everything earlier (we started earlier our work schedule, earlier walks with Vera, and earlier dinner), in order to be able to start with earlier bedtimes (Blog Post 61). So basically, I would say that it should be a change in the organization of the family structure/organization of schedules. So yes, I agree that the sleep problems would improve if the bedtime becomes earlier, but for that, in many cases, the parents would need to become “early birds”, instead of “night owls”, which was more common in their lifestyles before the baby was born (now I do not know what is on TV after 10PM ????).
Taken together, these 4 observations emphasize the importance of early bedtimes. The four published papers discussed in detail the importance of bedtime frequency, bedtime consistency, maternal sleep-related cognitive biases, and biological maturation of the baby’s circadian sleep-wake rhythm. But none of these papers actually discussed the importance of early bedtimes. However, all four authors, when they reanalyzed their data at my request, observed that early bedtimes were a strong or the strongest factor promoting longer nighttime sleep.
Additionally, here are three more published studies where I asked the authors about the importance of an early bedtime:
- Dr. Miaobing Zheng (Blog Post 75) observed, in 2021, that in 315 Danish children between 2-6 years of age who were followed for 15 months, those children who showed an increase in sleep durations had better mental health outcomes compared to those who had the no change or a decrease in their sleep durations. I asked her whether the quality of night sleep (Blog Post 15) might be more important than the duration of sleep. Specifically, on the importance of an early bedtime as a contributor to better quality sleep? Her response: “This is a great point and I couldn’t agree more.”
- A 2022 paper concluded that “Our study found that night waking frequency associates with higher number of mental health problems in adolescents at the ages of 13-14 years old. I asked an author to analyze the relationship between night waking frequency and the bedtime and she observed that they were correlated with each other. I then asked her if the correlations had been presented and discussed in the paper, would the ‘Conclusion’ in the abstract have included ‘the bedtime’ as in “Further special attention should be given to gender differences and the bedtime when addressing sleep and mental health’? She responded: “Yes, I agree that for future research it would be good to pay further attention to the role of the bedtime.”
- A 2022 paper observed “An interaction between bedtime and preschool depression severity, indicating that children with the earliest bedtimes and the lowest level of depression showed the largest grey matter volume (representing the concentration of nerve cell bodies in the brain).” In the context of multiple comparisons, this association did not reach statistical significance. However, early bedtimes were significantly associated with more sleep regularity and longer sleep durations. I asked the lead author, given these correlations, how to view the clinical importance of early bedtimes? She answered, “I think these results generally underscore the importance of early bedtimes in young children. We know exposures/experiences in early childhood can have long term effect on neurodevelopment, and late bedtimes may be one pathway through which maladaptive neurodevelopmental trajectories emerge.”
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