Sleep of Children with High Potentialities: A Polysomnographic Study. (2022). Key takeaway: High IQ kids had more REM sleep and less stage 1 sleep than controls, but also more insomnia and sleep complaints. The researchers hypothesized that high IQ children's increased REM sleep could be advantageous for learning.
Association Between Sleep Duration and Intelligence Quotient in 6-Year-Old Children. 2022. This study from South Korea found a significant association between IQ scores and sleep duration only in boys where boys who slept longer had better performance on some aspects of IQ testing. However, other research has suggested that sleep duration is not as important as sleep efficiency. For example, Association Between Sleep Duration and Intelligence Scores in Healthy Children found that higher IQ children had lower sleep duration, which they characterized as being nighttime efficient.
Sleep characteristics and socio-emotional functioning of gifted children. August 2021. Takeaway: Gifted children are more likely than peers to experience sleep difficulties. However, Sleep behaviors and handedness in gifted and non-gifted children (Sept 2021) and others did not find significant differences in sleep patterns between gifted and non-gifted children.
Circadian preference and intelligence - an updated meta-analysis. (2021). The researchers found no significant link between morningness and intelligence among the large sample, but they found a moderating effect for age. The morningness-intelligence correlation decreased with age moving from a non-significant positive trend in children and adolescents to a significant negative correlation after young adulthood. Eveningness was positively correlated with intelligence when based on an age-restricted sample. The researchers hypothesize that the age-moderated correlation between circadian preference and intelligence reflects social effects, where more intelligent individuals are more able to adjust their daily schedules to their natural circadian rhythm.
The relationship between chronotype and intelligence: the importance of work timing. 2020. Study found that there was no difference in chronotype between Mensa members and matched controls. Mensa members who had later sleep timing was due to later work start times and not physiological differences. The researchers hypothesize that later working times and associated lower social jetlag may be one of the reasons that those with higher IQ are associated with lower morbidity and mortality.
Age-related changes in sleep EEG are attenuated in highly intelligent individuals. 2017. Abstract: "Impaired sleep is a frequent complaint in ageing and a risk factor for many diseases. Non-rapid eye movement (NREM) sleep EEG delta power reflects neural plasticity and, in line with age-related cognitive decline, decreases with age. Individuals with higher general intelligence are less affected by age-related cognitive decline or other disorders and have longer lifespans. We investigated the correlation between age and EEG power in 159 healthy human subjects (age range: 17–69 years), and compared an average (IQ<120; N=87) with a high (IQ≥120; N=72) intelligence subgroup. We found less age-related decrease in all-night relative NREM sleep EEG delta power in the high intelligence subgroup. Our results suggest that highly intelligent individuals are less affected by the sleep-related effects of biological ageing, and therefore potentially less at risk for age-related cognitive deficits and other diseases."
The association between sleep spindles and IQ in healthy school-age children. 2013. Abstract: "Recent studies have suggested that sleep is associated with IQ measures in children, but the underlying mechanism remains unknown. An association between sleep spindles and IQ has been found in adults, but only two previous studies have explored this topic in children. The goal of this study was to examine whether sleep spindle frequency, amplitude, duration and/or density were associated with performance on the perceptual reasoning, verbal comprehension, working memory, and processing speed subscales of the Wechsler Intelligence Scale for Children-IV (WISC-IV). We recruited 29 typically developing children 7–11 years of age. We used portable polysomnography to document sleep architecture in the natural home environment and evaluated IQ. We found that lower sleep spindle frequency was associated with better performance on the perceptual reasoning and working memory WISC-IV scales, but that sleep spindle amplitude, duration and density were not associated with performance on the IQ test."
The function of the sleep spindle: A physiological index of intelligence and a mechanism for sleep-dependent memory consolidation. 2010. Researchers argue that sleep spindles (a feature of stage 2 non-REM sleep characterized by recurrent and brief bursts of spindle-like EEG activity) are related to intellectual ability and memory consolidation.
Why night owls are more intelligent. 2009. Researchers argue that more intelligent people tend to be nocturnal.