Temporal dynamics of circadian phase shifting response to consecutive night shifts in healthcare workers: role of light-dark exposure

AuthorsStone, J.E.
Sletten, T.L.
Magee, M
Ganesan, S.
Mulhall, M. D.
Collins, A.
Howard, M.
Lockley, S.W.
Rajaratnam, S. M. W.
TypeJournal Article (Original Research)
JournalThe Journal of Physiology
PubMed ID29589871
Year of Publication2018
URLhttps://www.ncbi.nlm.nih.gov/pubmed/29589871#
DOI/10.1113/jp275589
Download Stone_et_al-2018-The_Journal_of_Physiology.pdf (886.9 KB)
AbstractKEY POINTS: Shift work is highly prevalent and is associated with significant adverse health impacts. There is substantial inter-individual variability in the way the circadian clock responds to changing shift cycles. The mechanisms underlying this variability are not well understood. We tested the hypothesis that light-dark exposure is a significant contributor to this variability; when combined with diurnal preference, the relative timing of light exposure accounted for 71% of individual variability in circadian phase response to night shift work. These results will drive development of personalised approaches to manage circadian disruption among shift workers and other vulnerable populations to potentially reduce the increased risk of disease in these populations. ABSTRACT: Night shift workers show highly variable rates of circadian adaptation. This study examined the relationship between light exposure patterns and the magnitude of circadian phase resetting in response to night shift work. In 21 participants (nursing and medical staff in an intensive care unit) circadian phase was measured using 6-sulphatoxymelatonin at baseline (day/evening shifts or days off) and after 3-4 consecutive night shifts. Daily light exposure was examined relative to individual circadian phase to quantify light intensity in the phase delay and phase advance portions of the light phase response curve (PRC). There was substantial inter-individual variability in the direction and magnitude of phase shift after three or four consecutive night shifts (mean phase delay -1:08 +/- 1:31 h; range -3:43 h delay to +3:07 h phase advance). The relative difference in the distribution of light relative to the PRC combined with diurnal preference accounted for 71% of the variability in phase shift. Regression analysis incorporating these factors estimated phase shift to within +/-60 min in 85% of participants. No participants met criteria for partial adaptation to night work after three or four consecutive night shifts. Our findings provide evidence that the phase resetting that does occur is based on individual light exposure patterns relative to an individual's baseline circadian phase. Thus, a 'one size fits all' approach to promoting adaptation to shift work using light therapy, implemented without knowledge of circadian phase, may not be efficacious for all individuals.

http://www.ibas.org.au/what-we-do/publications/3872958


< More publications



CHEST-MND:PROCHEST-MND:PRO

Motor neurone disease (MND) causes the body's muscles to weaken. Breathing muscle weakness means that most people affected by MND will eventually lose the ability to take a deep breath and cough strongly....

Notch monitoring in sleepNOTCH MONITORING IN SLEEP

Sleep apnea is a condition where breathing is abnormal during sleep. There are two main forms of sleep apnea: obstructive and central. For obstructive sleep apnea, breathing is reduced because the airway...

Respiratory Biomarkers in Motor Neurone DiseaseRESPIRATORY BIOMARKERS IN MOTOR NEURONE DISEASE

The inability to breathe is unfortunately the most common cause of death in people living with Motor Neurone Disease (MND). Last year, our clinical research group in Melbourne reported that breathing...

Recognising research meritRECOGNISING RESEARCH MERIT

Kudos to Dr. Lauren Booker & Dr. Jen Cori on their JOEM publication examining fatigue detection alarms in rural truck drivers. Their study explores the alarms' effectiveness, accuracy, and habituation, offering key insights into fatigue management.

Honoring Excellence in ResearchHONORING EXCELLENCE IN RESEARCH

Congratulations to Prof. Anne Holland and A/Prof. Narelle Cox for being featured in the NHMRC's 10 of the Best - 16th Edition. Their work exemplifies groundbreaking research delivering extraordinary outcomes.

AMRF Grant Awards for 2025AMRF GRANT AWARDS FOR 2025

Grants Success: The Institute for Breathing and Sleep (IBAS) has received two research grants from the Austin Medical Research Foundation (AMRF) for 2025. Congratulations to Dr Charissa Zaga and Dr Catherine Hill from IBAS.

Recognition by MND AustraliaRECOGNITION BY MND AUSTRALIA

Congratulations to Professor David Berlowitz, Dr Marnie Graco, and Dr Nicole Sheers who were recognised by Motor Neurone Disease (MND) Australia at a Parliament House event sponsored by the Parliamentary Friends of MND in Canberra last week.

Institute for Breathing and Sleep

Level 5, Harold Stokes Building, Austin Health
145 Studley Road
Heidelberg, Victoria, 3084

(03) 9496 5390

Email Us

Donate