University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Consequences of Shift Work on Circadian Rhythms and Metabolism.

Gibbs, Michelle A. (2005) Consequences of Shift Work on Circadian Rhythms and Metabolism. Doctoral thesis, University of Surrey (United Kingdom)..

[img]
Preview
Text
11010023.pdf
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (22MB) | Preview

Abstract

This project investigated a series of shift schedules (14-Days, 14-Nights, 7-Night,7-Days, and 7-Days,7-Nights,) to determine circadian status (using the rhythm of urnary 6-sulphatoxymelatonin), sleep (by actigraphy) and selected metabolic parameters, in the offshore petrochemical industry, which operates a range of schedules with uncertain impact on biological rhythms and health. No circadian adaptation was observed in the 14-Days schedule. All subjects adapted to the 14-Nights schedule by circadian phase delay, and to the night shift of 7-Days,7-Nights by phase advance. On the 7-Nights,7-Days schedule the majority of subjects also adapted to the night shift by delay, but most did not re-adapt back to dayshift. The novel parameter 'Desynchrony Load' (cumulated deviation from ideal circadian timing, in hours) was used as a quantitative indicator of disruption. The 7-Nights,7-Days schedule gave the highest score (61.7h), 14-Nights, 7-days,7-nights and 14-Days gave 31.5, 26.2 and 13.9h respectively. The timing of light exposure in relation to circadian phase was identified as a major influence in adaptation. The 7-Nights,7-Days and 7-Days,7-Nights schedules impacted negatively on sleep, as the night after the swing-shift had the shortest sleep (shortest duration and longest latency). Sleep efficiency was significantly improved after the 7-Nights,7-Days rollover suggesting that returning to normal clock-time was associated with better sleep despite the desynchrony. There was no significant difference in overall macronutrient or energy intake between day and night shifts, despite a temporal redistribution of meal times. Postprandial TAG on night 2 (desynchronised) was raised compared with night 6 (adapted) of night shifts (14-Nights and nights of 7-Nights,7-Days). Similar trends were seen in postprandial cholesterol and insulin, but not in glucose. The improved TAG on night-6 seen in adapting subjects was still seen as a trend in non-adapters, suggesting that metabolic recovery may occur independently of, or faster than, the central circadian clock. In conclusion, the raised postprandial TAG on night-2 is evidence that shiftwork desynchrony may contribute to CVD risk via disturbance to normal metabolic processes. Finally, when night work is essential, the 14-Nights schedule is preferable to the schedules that impose a double desynchronisation.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Gibbs, Michelle A.
Date : 2005
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2005.
Depositing User : EPrints Services
Date Deposited : 30 Apr 2019 08:07
Last Modified : 20 Aug 2019 15:32
URI: http://epubs.surrey.ac.uk/id/eprint/851290

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800