Impacts of Night Shifts on Brain Connectivity and ALFF among Medical Personnel
Presented During:
Saturday, June 28, 2025: 11:30 AM - 12:45 PM
Brisbane Convention & Exhibition Centre
Room:
M1 & M2 (Mezzanine Level)
Poster No:
2086
Submission Type:
Abstract Submission
Authors:
Tengmao Yao1, Yu-Tang Tung2, Chih-Mao Huang3, Yi-Ping Chao4, Kuan-Wei Lee5, Chi-Yun Liu1, Yi-Chia Kung6, Changwei Wu1
Institutions:
1Taipei Medical University, New Taipei, Taiwan, 2National Chung Hsing University, Taichung, Taiwan, 3National Yang Ming Chiao Tung University, Hsinchu, Taiwan, 4Chang Gung University, Taoyuan, Taiwan, 5Taipei Medical University, Taoyuan, Taoyuan, 6National Defense Medical Center, Taipei, Taiwan
First Author:
Co-Author(s):
Introduction:
Night shift is a prevalent workstyle in medical hospitals, demanding continuous health monitoring and rapid decision making of medical professionals. Night shifts may cause serious health problems to medical staff, including cognitive impairments, poor sleep, and lowered brain functionality [1, 2]. In the Taiwanese medical field, the consecutive rotation of 3–5-night shifts in a row are a common schedule across medical staffs [3]. However, how long the aversive impact lasts remain to be studied. Hence, we designed repeated measures of brain functions following the night shifts and subsequent recovery among medical shift workers. Accordingly, we hypothesized that the functional connectivity in default-mode network (DMN) and dorsal attention network (DAN) may be altered after night shifts and recovered after circadian realignments, as well as the functional index of amplitude of low-frequency fluctuations (ALFF).
Methods:
We recruited 15 medical personnel from hospitals in Taipei. All participants were instructed to visit the MRI center for three times to assess the effects of shift work in a repeated-measure design. The three time points contained (a) before starting their shift work (pre-shift), (b) after working in night shift for at least four days (post-shift), and (c) at least three days of back-to-normal-sleep after shift days (recovery). All participants were instructed to wear actigraphy to measure their total sleep time (TST), sleep efficiency (SE), and wake after sleep onset (WASO). Each MRI experiment was conducted with a 3T PRISMA scanner at National Taiwan University. The rs-fMRI scans were using gradient-echo EPI sequence with voxel size = 3.44×3.44×3.4 mm3; TR/TE= 2000/32 msec, FA= 77°; total scan time = 7 min. CONN toolbox was used for image analysis to generate the seed-based FC of DMN and DAN, as well as ALFF. R software (4.3.3) was used for data analysis after the ROI extraction. Statistically, we performed one-way repeated-measure ANOVA for between-session comparison on sleep metrics, and brain functional indices with post-hoc tests, where the statistical significance was set as p < 0.05 with Bonferroni correction.
Results:
Ten out of fifteen participants completed the entire procedure of three repeated measures in night shifts. The average time spans of the night-shift and recovery days were 5.6±1.0 and 4.1±1.4 days, respectively. Figure 1 shows the sleep metrics during the experimental procedure was shown in. After the shift work, reduced TST was prominent, rebounded back in recovery days, indicating a partial sleep deprivation during the night shift (p = 0.007). SE and WASO did not present significant changes. In ALFF, the superior frontal gyrus (SFG) exhibited a significant time effect on ALFF (p < 0.001), revealing that the medical staff had elevated ALFF after shift work (p = 0.022) but returned to the baseline after recovery (p < 0.001). Figure 2b and 2c exhibit the FC changes of DMN and DAN, respectively, across the 3 measures over the shift work. In DMN (Figure 2b), we observed the time effect on the FC between PCC and thalamus (p < 0.001), indicating that a significant reduction of FC(PCC-thalamus) in the post-shift session (pre-shift vs. post-shift: p < 0.001) remained low in the recovery days (post-shift vs. recovery: p = 0.65). In DAN, the time effect was found on the FC between the IPS and the precentral gyrus (PreCG) (p < 0.001), indicating an elevated FC(IPS-PreCG) in the post-shift session (pre-shift vs. post-shift: p < 0.01).
·Figure 1. Sleep metrics over the consecutive night shifts (before, after and recovery) in medical staff. (a) total sleep time; (b) sleep efficiency; (c) wake after sleep onset (WASO).
·Figure 2. Brain functionality over the consecutive night shifts (before, after and recovery) in medical staff. (a) ALFF; (b) FC of default-mode network (DMN, seeding at posterior cingulate cortex) con
Conclusions:
After 5-day night shifts, medical staffs experienced partial sleep deprivation indeed, and the impact of night shifts on brain functions was tested following 4-day recovery (rest days). The ALFF in SFG, an insomnia index [4], indeed recovers after rest days, but the FC(PCC-thalamus), a fatigue index [5], did not recover after rest days. The three repeated measures disclosed that the altered brain functions may not fully recovered after 4 days of circadian realignments in medical personnel.
Higher Cognitive Functions:
Executive Function, Cognitive Control and Decision Making
Modeling and Analysis Methods:
Task-Independent and Resting-State Analysis 2
Perception, Attention and Motor Behavior:
Sleep and Wakefulness 1
Keywords:
Anxiety
FUNCTIONAL MRI
NORMAL HUMAN
Sleep
1|2Indicates the priority used for review
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2 Brown, C., Abdelrahman, T., Lewis, W., Pollitt, J., Egan, R., Abdulal, S., et al. (2020). To bed or not to bed: the sleep question? Postgrad. Méd. J. 96, 520–524.
3 Chang, Y.-S., Wu, Y.-H., Chen, H.-L., and Hsu, C.-Y. (2017). Four Night Shifts Have a Degree of Performance Adaptation. Hum. Factors: J. Hum. Factors Ergon. Soc. 59, 925–936.
4 Hsiao, F.-C., Tsai, P.-J., Wu, C.W., Yang, C.-M.*, Lane, T.J.*, Lee, H.-C., Chen, L.-C., Lee, W.-K., Lu, L.-H., Wu, Y.-Z. (2018) The Neurophysiological Basis of the Discrepancy between Objective and Subjective Sleep during the Sleep Onset Period: an EEG-fMRI study. Sleep, zsy056
5 Tsai, P.-J., Chen, C.-J., Hsu, C.-Y., Wu, C.W.*, Wu, Y.-C., Hung, C.-S., Yang, A.C., Liu, P.-Y., Biswal, B., Lin, C.-P. (2014) Local Awakening: Regional Reorganizations of Brain Oscillations after Sleep. Neuroimage, 102; 894-903.