The science of bedtime. Why 7-8pm is the optimal sleep time for babies and toddlers? -

Putting a child to bed at a consistent time each night is a challenge many parents face, myself included. Despite my efforts with sleep training, I’ve found it really difficult to get my 21-month-old baby to fall asleep before 8:30 PM. I start her bedtime routine at 7 PM, in bed by 7:30 PM, but it often takes her about an hour of playing before she finally drifts off to sleep. Curious about the impact of her later bedtime, I decided to delve into the research to understand what it means for her development and well-being. What I discovered is that while the impact of sleeping at 8:30 PM isn’t as significant, the negative effects become much more pronounced after 9:00 PM. Armed with this knowledge, my strategy is to gradually move her bedtime earlier by 15 minutes at a time, with the goal of helping her fall asleep before 8:30 PM.

Key Takeaways:

Optimal Bedtime: Research suggests that children should ideally go to bed between 7:00 PM and 8:00 PM, aligning with their natural circadian rhythms.
Impact of Later Bedtimes: Bedtimes after 8:30 PM can start to affect sleep quality and behavior, but the most significant negative effects are seen with bedtimes after 9:00 PM.
Strategies for Parents: Gradually adjusting bedtime by 15-minute increments can help shift a child’s sleep schedule earlier, improving sleep quality and overall well-being.

Understanding sleep needs by age

Before diving into the specifics of bedtime, it’s important to understand how much sleep children need at different stages of development:

Infants (4-12 months): 12-16 hours, including naps
Toddlers (1-2 years): 11-14 hours, including naps
Preschoolers (3-5 years): 10-13 hours, including naps
School-aged children (6-12 years): 9-12 hours
Teens (13-18 years): 8-10 hours

These recommendations, provided by the American Academy of Sleep Medicine, serve as a baseline for understanding how sleep contributes to healthy growth and development.

The optimum bedtime

For most children, the optimal bedtime falls between 7:00 PM and 8:00 PM. This time range is supported by research and aligns with children’s natural circadian rhythms, which tend to favor an earlier sleep schedule. Here’s a closer look at why this window is ideal:

Circadian rhythm: Children, particularly younger ones, have a circadian rhythm that predisposes them to feel sleepy in the early evening. Melatonin, the hormone responsible for regulating sleep, typically begins to rise in children around 6:00 PM to 7:00 PM, leading to natural drowsiness by 7:00 PM to 8:00 PM.
Sleep quality: The Pediatrics study by Mindell et al. shows that children who go to bed earlier generally experience longer and higher-quality sleep. This is crucial for processes such as memory consolidation, growth, and emotional regulation.
Behavioral benefits: Early bedtimes are associated with better daytime behavior, including improved attention, emotional regulation, and fewer instances of hyperactivity or aggression. Children who consistently go to bed between 7:00 PM and 8:00 PM are more likely to exhibit positive behaviors and perform better academically.

What happens with a later bedtime?

While the optimum bedtime is well-established, what happens when children go to bed later? Research indicates that a later bedtime can have several negative impacts, particularly if the bedtime shifts past 8:30 PM. Here’s what the science says:

Reduced sleep duration:
- The Journal of Pediatrics study by Kelly et al. found that children with bedtimes after 9:00 PM generally slept less overall compared to those with earlier bedtimes. Since wake-up times often remain fixed due to school or daily routines, later bedtimes reduce the total amount of sleep a child receives.
- Impact: Insufficient sleep can lead to a host of issues, including irritability, difficulty concentrating, and impaired cognitive function.
Sleep disruptions:
- The Journal of Pediatrics study also suggests that children who go to bed later are more likely to experience fragmented sleep, including more frequent awakenings during the night.
- Impact: Disrupted sleep can affect a child’s ability to stay alert during the day and can contribute to emotional and behavioral problems.
Behavioral and cognitive issues:
- The study published in Child Development by Wang et al. showed that children with later or irregular bedtimes were more likely to exhibit behavioral problems, such as tantrums, hyperactivity, and difficulty paying attention. These children also performed worse on cognitive tests, indicating that late bedtimes can negatively impact learning and development.
- Impact: These issues can compound over time, affecting a child’s academic performance and social relationships.

Defining “later” bedtimes

The term “later bedtime” is relative but generally refers to any bedtime that falls after the child’s natural circadian preference or pushes past recommended sleep windows. Specifically:

Moderately later: 8:30 PM to 9:00 PM
Significantly later: After 9:00 PM

The impact of a later bedtime is more pronounced as the bedtime gets pushed further into the night. Bedtimes after 9:00 PM are most strongly associated with reduced sleep duration, poor sleep quality, and negative behavioral outcomes.

Practical recommendations for parents

Set consistent bedtimes: Aim to establish and maintain a consistent bedtime between 7:00 PM and 8:00 PM for younger children. This consistency helps reinforce their circadian rhythm and improves sleep quality.
Create a soothing bedtime routine: Engage in calming activities before bed, such as reading or bath time, to help your child wind down and prepare for sleep. Read in details how to setup a bedtime routine.
Monitor sleep needs: Pay attention to your child’s sleep patterns and adjust their bedtime as needed to ensure they are getting enough rest. For example, if your child is consistently waking up too early or struggling to stay awake during the day, an earlier bedtime might be necessary.
Avoid late-night stimulants: Limit exposure to screens and avoid stimulating activities in the hour leading up to bedtime. Blue light from screens can interfere with melatonin production, making it harder for your child to fall asleep.