Table 3.
Association between sleep duration and cognitive development in children aged 0–4 years
| No of studies | Design | Quality Assessment | No of participants | Absolute effect | Quality | ||||
|---|---|---|---|---|---|---|---|---|---|
| Risk of bias | Inconsistency | Indirectness | Imprecision | Other | |||||
| Mean age ranged between 6 months and 4.9 years. Data were collected cross-sectionally and up to 3 years of follow-up. Sleep duration was assessed by actigraphy or parent report. Cognition was measured by various instruments including memory tasks, imitation tasks, neuropsychological tests, interviews, scales of intelligence or questionnaires. | |||||||||
| 1 | Randomized triala | No serious risk of bias | No serious inconsistency | No serious indirectness | No serious imprecision | None | 23 | The number of correct answers in an explicit recognition task was significantly higher in the nap (control) compared to the wake (sleep-restricted) condition, whereas implicit memory (priming task) did not differ between conditions [65]. | HIGH |
| 4 | Longitudinal studyb | No serious risk of bias | No serious inconsistency | No serious indirectness | No serious imprecision | None | 438 | Children getting higher proportions of their sleep at night as infants (i.e. 1 year) were found to perform better on executive functions, but did not show better general cognition [66]. Higher proportions of total sleep occurring at night time, at both 12 and 18 months, were associated with better performance on executive tasks, especially those involving a strong impulse control component. However, the total sleep duration at 12 and 18 months was not associated with executive functioning at 18 and 26 months. Sleep duration at 12 months was not correlated with 18 month working memory (r = −0.11, p > 0.05), 26 month conflict executive functioning (r = −0.10, p > 0.05) or 26 month impulse control (r = −0.06, p > 0.05). Sleep duration at 18 months was not correlated with 18 month working memory (r = −0.16, p > 0.05), 26 month conflict executive functioning (r = 0.09, p > 0.05) or 26 month impulse control (r = −0.16, p > 0.05) [67]. The number of daytimenaps was positively associated with both predicted expressive (p = 0.062) and receptive vocabulary growth (p = 0.006), whereas the length of nighttime sleep was negatively associated with rate of predicted expressive vocabulary growth (p = 0.045) [68]. Children who had 8 h or more of sleep had significantly higher General Conceptual Ability (GCA) scores than those with 7 h or less of sleep by 35.53 points at age 3. Children with more than 10 h of sleep had higher GCA scores at age 3 compared to children with 8–9 h or less of sleep (233.91 vs. 203.92, respectively) [69]. |
LOW |
| 11 | Cross-sectional studyc | No serious risk of bias | No serious inconsistency | No serious indirectness | No serious imprecision | None | 10,838 | Out of 11 cross-sectional analyses, 7 reported null findings [38, 51, 55, 70–73], 3 reported that shorter sleep duration was associated with poorer cognitive function [57, 74, 75], and 1 reported opposite associations [76]. | LOW |