In our fast-paced society, sleep deprivation has become a common occurrence, with detrimental effects on various cognitive processes such as attention, memory, and emotional control. Recent research has suggested that higher intelligence might serve as a protective factor against the negative impact of sleep loss.
To shed light on this intriguing relationship, a study published in the Journal of Sleep Research aimed to investigate whether individuals with higher intelligence are more resilient to the effects of sleep deprivation or if the previous findings were simply a result of overall superior cognitive performance.
The study involved 182 healthy individuals who were randomly assigned to either a sleep-deprivation condition or a normal-sleep condition. Participants were assessed on various cognitive tasks, including arithmetic ability, episodic word memory, spatial working memory, and simple attention.
To measure fluid intelligence, researchers used the Raven’s Test, a non-verbal multiple-choice assessment where participants completed patterns by identifying the missing element from a set of alternatives, ultimately completing a larger pattern.
As expected, the researchers found that fluid intelligence, which refers to the ability to solve problems and think logically, is related to better performance in tasks involving arithmetic accuracy, speed, and remembering words.
But the researchers also observed an interesting finding. Contrary to expectations, individuals with higher fluid intelligence actually made more mistakes on the arithmetic test, as well as in the episodic word memory and spatial working memory tests, after experiencing sleep deprivation compared to those who had a normal night’s sleep. However, there were no significant differences between the groups in terms of reaction times and subjective sleepiness.
This study provides evidence that higher fluid intelligence does not offer protection against the negative cognitive effects of sleep loss. These findings are surprising because intelligence has been linked to protection against other types of stress, such as interpersonal stress.
The researchers argue that higher-order cognitive functions, which involve complex thinking and problem-solving, are positively related to intelligence only when sleep conditions are optimal. However, these functions become more vulnerable to sleep loss.
It is important to note that this particular study focused on total sleep deprivation for just one night, and thus, the possibility that intelligence may serve as a buffer against severe sleep loss cannot be ruled out.
Additionally, the study design, which involved comparing different individuals rather than the same individuals across conditions, has its limitations. Further research is needed to delve deeper into this complex relationship between sleep, intelligence, and cognitive performance.
“In conclusion, these data indicate that fluid intelligence is related to superior higher-order cognitive functioning under optimal sleep conditions, but that it does not protect against the deleterious cognitive effects of sleep loss,” the researchers wrote. “While intelligence has previously been shown to protect against the effects of different stressors, it was here related to an increased vulnerability to sleep loss for higher-order cognitive functions.”
“Further studies may test whether the cognitive benefits of intelligence are primarily limited to optimal situations and whether it predicts avoidance of stressful situations or other strategies that safeguard optimal cognitive functioning.”
The study, “Intelligence predicts better cognitive performance after normal sleep but larger vulnerability to sleep deprivation“, was authored by Leonie J. T. Balter, Tina Sundelin, Benjamin C. Holding, Predrag Petrovic, and John Axelsson.