Exploring the relationship between early cognitive ability and age-60 sleep quality: The Newcastle Thousand Families...

Poor sleep quality has been linked to adverse health outcomes. It is important to understand factors contributing to sleep quality. Previous research has suggested increased cognition and education duration have a protective effect on sleep quality in old age. This study aimed to assess the hypothesis that age-11 intelligence quotient and highest achieved education level are associated with subjective sleep quality at age 60.

Participants are members of the Newcastle Thousand Families Study birth cohort, all born in 1947. Data included a calculated intelligence quotient score based on participant's 11-plus exam results, highest achieved education level, social class at ages 25 and 50 and global Pittsburgh Sleep Quality Index (PSQI) at age 60. Multivariable regression analysis was used to investigate effect sizes of variables on global PSQI, which formed the basis of a path analysis model.

After excluding participants with incomplete data, and those who had been diagnosed with sleep apnea, 251 participants were included in the path analysis model. Education level was associated with global PSQI (R=-0.653; 95% CI -1.161, -0.145; P = .012) but age-11 intelligence quotient was not. While a similar association was seen for women in the stratified analysis, no such associations were seen for men.

The results of this study show an inverse relationship between education level, but not childhood intelligence quotient, and sleep quality in later life, in women only. Future research is needed to examine the mechanism underlying this relationship.