Impact of sleep disturbance in shift workers on hippocampal volume and psychomotor speed

Yumi Song; Shinhye Kim; Yoonji Joo; Eunji Ha; Youngeun Shim; Hyeonji Lee; Hyeonseok Jeong; In Kyoon Lyoo; Sujung Yoon; Suji Lee

doi:10.1093/sleep/zsae100

Impact of sleep disturbance in shift workers on hippocampal volume and psychomotor speed

Sleep. 2024 Apr 26:zsae100. doi: 10.1093/sleep/zsae100. Online ahead of print.

Authors

Yumi Song^{1

2}, Shinhye Kim^{1

2}, Yoonji Joo¹, Eunji Ha¹, Youngeun Shim^{1

2}, Hyeonji Lee^{1

2}, Hyeonseok Jeong³, In Kyoon Lyoo^{1

2

4}, Sujung Yoon^{1

2}, Suji Lee⁵

Affiliations

¹ Ewha Brain Institute, Ewha Womans University, Seoul, South Korea.
² Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul, South Korea.
³ Department of Radiology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
⁴ Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, South Korea.
⁵ College of Pharmacy, Dongduk Women's University, Seoul, South Korea.

PMID: 38666299
DOI: 10.1093/sleep/zsae100

Abstract

Study objectives: Shift work interferes with circadian rhythms, affecting sleep quality and cognitive function. Poor sleep quality in shift workers can impair psychomotor performance due to fatigue and sleepiness, increasing the risk of errors, accidents, and reduced productivity. Given the potential for atrophic changes in the hippocampus due to sleep disturbances, our study investigates how poor sleep quality correlates with hippocampal structural alterations and impacts psychomotor performance among shift workers.

Methods: We recruited 100 shift workers, classifying them based on sleep quality into two groups: good sleep-SW group (n = 59) and poor sleep-SW group (n = 41). Sleep quality was assessed using both 7-day actigraphy for sleep efficiency and the Pittsburgh Sleep Quality Index. A control group of 106 non-shift workers without sleep problems (non-SW group) was also included for comparison. The outcome measures were psychomotor speed and hippocampal volumes, both total and by subfield.

Results: The poor sleep-SW group showed significantly smaller hippocampal volumes than both the good sleep-SW group (P<0.001) and the non-SW group (P=0.003). Longer shift work years correlated with greater reductions in hippocampal volume in this group (r=-0.42, P=0.009), unlike in the good sleep-SW group (r=0.08, P=0.541). Furthermore, they demonstrated declines in psychomotor speed relative to the non-SW group (P=0.006), which correlated with smaller hippocampal volumes (r=0.37, P=0.020).

Conclusions: Shift workers with poor sleep quality exhibit significant hippocampal volume reductions and psychomotor speed decline, underscoring the importance of early intervention and support for sleep issues in this population.

Keywords: hippocampus; psychomotor speed; shift work; sleep disturbance.

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