Original ArticleSleep quality and cognitive performance in 8-year-old children
Introduction
Adequate sleep is generally considered essential for children’s well-being and development. While several studies have linked various sleep-related problems to lower school performance [1] or behavioural problems [2], [3], [4], [5], the particular cognitive domains affected by poor sleep quality are not well characterized among children. Three previous cross-sectional studies have shown poor sleep quality leads to impairments in attention, reaction time, and working memory (Table 1). Children with poor sleep quality or short sleep duration had more errors in the Continuous Performance Test (CPT) and a symbol digit substitution task [6] and higher error rates in one-back or two-back working memory tasks [7]. A recent study also linked poor sleep quality with worse processing speed and verbal ability [8].
Some experimental studies in child populations have also been performed. Even though they do not tell how sleep quality and performance are connected on a population level, they are important in assessing the cause-effect pathway. The first experimental studies, more than 25 years ago, showed that one-night total sleep restriction in adolescents results in lower performance in an arithmetic test, a declarative memory test and a verbal short-term memory test [9], [10]. More recently, it has been shown that partial sleep deprivation has rather similar consequences: sleep restriction to 5 h for one night impaired fluency and originality of thinking as well as learning of abstract concepts [11]. Moreover, children in a sleep restriction group (4 h vs. 10 h for one night) were reported to be more inattentive and had more commission errors and longer delays in the CPT than those sleeping more [12]. Sleep restriction of even milder degrees can have an impact on performance if it is persistent. In two different studies, children with restricted and optimized sleep duration conditions were compared in slightly different sleep manipulation protocols. In the first study, restricting or extending sleep duration by at least 30 min for three days affected children’s neurocognitive performance: sleep extension improved attention in a working memory task (digit span forward) and shortened simple reaction time. Sleep restriction, in turn, led to deterioration in reaction time [13]. Finally, a cross-over study with sleep restriction or extension conditions for a week showed sleep restriction to be related to academic problems and inattentiveness as reported by school teachers [14]. Overall, the findings in experimental studies are consistent, which argues for a cause-effect pathway: sleep restriction impairs and sleep extension improves attention and working memory.
A recent longitudinal study found an association between shorter sleep duration in early childhood and worse verbal and visuospatial performance at school entry [15], suggesting that sleep disruption in early childhood may indicate, or maybe even induce, deficits in cognitive functioning. Even though the neural mechanism beyond this association remains to be determined, it is worth noticing that prolonged sleep deprivation has been shown to inhibit neurogenesis in the hippocampus through elevated glucocorticoids [16]. As children’s sleeping difficulties have been linked with increased cortisol levels [17], [18], this may provide one potential biological mechanism to connect poor sleep and cognitive functioning during early childhood.
The current knowledge is, however, still limited, even though the need for well-controlled studies was underlined already over a decade ago in 1996 [19]. Firstly, previous studies have been based on a rather fragmented set of cognitive tests; which particular cognitive domains are affected by inadequate sleep among children remains undetermined. Secondly, previous studies have included children over a wide age span, but age is a significant confounding factor, being closely related both to sleep requirements and cognitive performance. The present study aims to extend the previous findings by including a more extensive cognitive test battery, with three tests for visuospatial skills, two tests for verbal skills and one for memory. The primary objective of the study was to test whether short sleep duration and poor sleep quality, as measured by both actigraphs and parental reports, are related to visuospatial and verbal performance in eight year-old children. As a secondary objective, we assessed specific cognitive subdomains as outcomes. We hypothesized that both short sleep duration and poor sleep quality would be related to worse performance.
Section snippets
Study setting
The study sample was derived from an initial cohort of 1049 mothers and their infants born between 1st March and 30th November 1998 in a large maternity hospital in the city of Helsinki, Finland, which has approximately 4500 births per year. The eligible infants were defined as those born as healthy singletons having a gestational age of 35–42 weeks [20]. In 2006, the children and their parents were invited to participate in a follow-up study with a focus on physical and psychological
Statistical methods
A maximum likelihood factor analysis was performed to summarize the six cognitive tests (Table 2). Two factors (visuospatial and verbal abilities) were extracted after Varimax rotation. The factor scores were calculated using the regression method and were used in further statistical analysis as dependent variables. Pearson’s correlation coefficients were calculated to compare sleep duration and cognitive performance. Average cognitive performance was compared in children with poor vs. good
Results
Table 3 shows characteristics of the sample.
In crude (unadjusted) analyses, sleep duration correlated with visuospatial abilities (overall sleep duration r = 0.14, p = 0.028; sleep duration on weekdays r = 0.12, p = 0.052; sleep duration on weekends r = 0.15, p = 0.015), but not with verbal abilities (all p-values ⩾0.67). Children with low sleep efficiency had significantly lower scores in Similarities than those with better sleep efficiency (mean ± SD, 9.89 ± 2.64 vs. 11.46 ± 3.29, p = 0.017, effect size 0.48,
Discussion
Our study is one of only a few to compare children’s objectively measured sleep duration and cognitive performance without experimental modification of sleep schedules in a large, representative community sample. Consistent with other such studies [6], [7], [8], we found that short sleep duration and poor sleep quality were related to lower performance in cognitive tests, but the association was not very strong. Shorter sleep duration was related to worse performance in visuospatial abilities
Sources of funding
This study was supported by grants from the Academy of Finland, the University of Helsinki, the European Science Foundation (EUROStress), the Juho Vainio Foundation, the John D. and Catherine T. MacArthur Foundation, the Finnish Foundation for Pediatric Research, the Signe and Ane Gyllenberg Foundation and the Yrjö Jahnsson Foundation.
Conflict of interest statement
The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
Acknowledgements
The study was carried out by the Department of Psychology, University of Helsinki, Finland and the National Institute for Health and Welfare (previously National Public Health Institute), Helsinki, Finland.
References (40)
- et al.
Understanding adolescents’ sleep patterns and school performance. a critical appraisal
Sleep Med Rev
(2003) - et al.
Sleep and psychiatric symptoms in school-age children
J Am Acad Child Adolesc Psychiat
(2000) - et al.
Working memory and sleep in 6- to 13-year-old schoolchildren
J Am Acad Child Adolesc Psychiat
(2003) - et al.
Electroencephalographic sleep profiles and hypothalamic-pituitary-adrenocortical (HPA)-activity in kindergarten children: early indication of poor sleep quality associated with increased cortisol secretion
J Psychiat Res
(2008) The impact of inadequate sleep on children’s daytime cognitive function
Seminars Pediat Neurol
(1996)- et al.
Comparison of actigraphic, polysomnographic, and subjective assessment of sleep parameters in sleep-disordered patients
Sleep Med
(2001) - et al.
Sleep in children with attention-deficit hyperactivity disorder (ADHD): a review of naturalistic and stimulant intervention studies
Sleep Med Rev
(2004) Attention deficit disorders: are we barking up the wrong tree
Eur J Pediat Neurol
(2006)The ADHD and sleep conuncdrum redux moving forward
Sleep Med Rev
(2006)- et al.
Short sleep duration and behavioral symptoms of attention-deficit/hyperactivity disorder in healthy 7- to 8-year-old children
Pediatrics
(2009)
Short sleep duration in middle childhood: risk factors and consequences
Sleep
Parents’ reports of disturbed sleep in 5–7-year-old Swedish children
Acta Paediatr
Sleep, neurobehavioral functioning, and behavior problems in school-age children
Child Dev
Children’s sleep and cognitive functioning: race and socioeconomic status as moderators of effects
Child Dev
Sleep loss in young adolescents
Sleep
Acute restriction of sleep in children
Percept Motor Skills
Cognitive function following acute sleep restriction in children ages 10–14
Sleep
Effects of acute sleep restriction on behavior, sustained attention, and response inhibition in children
Percept Motor Skills
The effects of sleep restriction and extension on school-age children: what a difference an hour makes
Child Dev
Experimental restriction of sleep opportunity in children: effects on teacher ratings
Sleep
Cited by (67)
Association between sleep hours and changes in cognitive function according to the morningness-eveningness type: A population-based study
2024, Journal of Affective DisordersEmotion regulation difficulties and sleep quality in adolescence during the early stages of the COVID-19 lockdown
2023, Journal of Affective DisordersAssociations between parental relationship dissolution and child sleep: A systematic review
2023, Sleep Medicine ReviewsSleep disorder as a clinical risk factor of major depression: associated with cognitive impairment
2022, Asian Journal of PsychiatryCitation Excerpt :A recent study demonstrated the significant associations among depression, sleep and cognition in older adults with mild cognitive impairment, which hinted the involvements of depression and sleep in cognitive impairment (Song et al., 2021). The relationship between short sleep duration and poor visuospatial/constructional function was observed in 8-year-old children (Paavonen et al., 2010). Thus, the SD effect on MDD cognition might be involved in the potential neurobiological underpinnings of the relationship between SD and cognitive impairment (Killgore et al., 2015; Ward et al., 2013).
Sleep Disorders in Children and Adolescents
2022, Comprehensive Clinical Psychology, Second EditionNewly walking infants’ night sleep impacts next day learning and problem solving
2021, Advances in Child Development and BehaviorCitation Excerpt :Research with children has demonstrated nuanced differences between the negative effects of fragmentation and total sleep duration on cognitive performance (Dewald-Kaufmann et al., 2010). For example, while short sleep durations were associated with poorer visuospatial skills, sleep quality was uniquely linked to children's ability to engage in abstract thinking (Paavonen et al., 2010). Targeted investigations of the relation between sleep and learning in infants are needed.