Children can be masterful at trying to get out of a regular bedtime. As clever as they may be in avoiding going to bed, that cleverness may not pay off for them later on.
A recent study found that not having a regular bedtime for children was linked to poorer test scores.
Whether children's scores were affected by bedtimes appeared to depend on the children's ages when they had irregular bedtimes.
Having an irregular bedtime at age 3, for example, appeared to have an effect on boys' and girls' cognitive skills at age 7.
This study, led by Yvonne Kelly, PhD, of the Department of Epidemiology and Public Health at University College London in the United Kingdom, looked at whether kids' bedtimes appeared related to their brain development.
The researchers compared the bedtimes and test scores for 11,178 children, all aged 7. The test scores examined were for reading, math and spatial abilities.
The researchers found that irregular bedtimes were related to lower test scores in reading, math and spatial skills for 7-year-old girls, but not for boys.
However, both boys and girls who did not have regular bedtimes when they were 3 years old had slightly poorer scores on all three subjects' tests when they were 7 years old than those who had regular bedtimes at age 3.
The researchers also found that the differences in test scores linked to irregular bedtimes added up over time.
For example, girls who did not have regular bedtimes when they were 3, 5 and 7 years old had lower scores than other girls who had regular bedtimes at all three ages or even at one or two of these ages.
Meanwhile, boys who did not have a regular bedtime at two of three ages — 3, 5 or 7 years old — had lower scores than boys who had regular bedtimes at these ages.
These findings cannot prove that not having a bedtime caused the difficulties with children's cognitive development.
However, the researchers did attempt to take into account a large number of factors that might have influenced a child's cognitive performance on tests besides bedtime.
These other factors included, among many others, the following:
- child's school year
- the mother's age
- languages spoken in the home
- family income
- the parents' education level and employment status
- the mother's psychological distress (based on a questionnaire)
- discipline strategies in the home
- whether the child was breastfed
- whether the mother smoked or drank alcohol during pregnancy
- whether the mother said she was often irritated with child
- daily activities of the child (music, art, help with reading)
- hours spent in front of TV and computer screens
- whether the parents felt they had enough time with their child
- whether the child attended before or after school clubs
- how often the parents read or told stories to the child
The researchers also took into account factors that might influence the quality of a child's sleep. These included having more than one person in the bedroom where the child slept, whether the child wet the bed and whether a TV was in the child's bedroom.
"It might be that inconsistent bedtimes are a reflection of chaotic family settings and it is this, rather than disrupted sleep that impacts on cognitive performance in children," the researchers wrote.
"However, we found that inconsistent bedtimes were linked to markers of cognitive performance independent of multiple markers of stressful family environments," they wrote.
The authors suggested that irregular bedtimes have the potential to influence children's cognitive development in two ways.
Not having a regular bedtime could possibly affect a child's circadian rhythms, the internal body clock that regulates a person's biological activities.
Or, it is possible that irregular bedtimes are related to sleep deprivation in the child, and the child's brain is being affected by sleep deprivation.
"The consistent nature of bedtimes during early childhood is related to cognitive performance," the researchers wrote. "Given the importance of early child development, there may be [future] effects for health throughout life."
The researchers acknowledged that it can be difficult for many families to keep consistent bedtimes for children.
"Families are prone to demands on time that might adversely impact the routines important for healthy development in young children," the researchers wrote.
They suggested families need better support in establishing regular bedtimes for children.
This study was published July 8 in the Journal of Epidemiology and Community Health.
The research was funded by the Economic and Social Research Council. The authors declared no conflicts of interest.