Research Paper|Volume 12, Issue 20|pp 20623—20644

Improvement in sleep duration was associated with higher cognitive function: a new association

Jianian Hua^1,², Hongpeng Sun³, Yueping Shen⁴

¹Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, PR China
²Medical College of Soochow University, Suzhou 215123, PR China
³Department of Child Health, School of Public Health, Medical College of Soochow University, Suzhou 215123, PR China
⁴Department of Epidemiology and Biostatistics, School of Public Health, Medical College of Soochow University, Suzhou 215123, PR China

Received: May 19, 2020Accepted: August 8, 2020Published: October 20, 2020

Copyright: © 2020 Hua et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Objectives: Previous studies have indicated that improvement in sleep duration might correlate with better cognition. We aimed to examine the associations between changes in sleep duration and cognitive function.

Results: A change from short sleep duration (SSD) to moderate sleep duration (MSD) was associated with better global cognition scores (β=0.54, P <0.01). A change from SSD to long sleep duration (LSD) (β=-0.94, P <0.001) or a change from LSD to SSD (β=-1.38, P <0.01) was associated with lower global cognition. For individuals with MSD, a≥2 h increase (β=-0.89, P <0.001) or decrease (β=-0.70, P <0.001) in sleep duration was associated with lower global cognition.

Conclusions: For short sleepers, improvement in sleep duration correlated with better cognition. For long sleepers, there was no need to reduce sleep duration. Excessive changes or deviation from the moderate duration was associated with lower cognition.

Methods: A total of 10325 individuals aged 45 and older from the China Health and Retirement Longitudinal Study (CHARLS) were included. Self-reported nocturnal sleep duration and cognitive function were assessed in the three waves of CHARLS from 2011 to 2015. Cognitive function was assessed by a global cognition score, which included episodic memory, visuospatial abilities, calculation, orientation and attention.