On December 31, 2020 the four UK Chief Medical Officers (CMOs) published a statement announcing changes to the dosing schedule for the second dose of the Pfizer/BioNTech and University of Oxford/AstraZeneca vaccines. It stated that the interval between the first and second dose should be extended from 3–4 weeks to up to 12 weeks. This rapid response examines the evidence behind this decision.
Documents to download
Shift Work, Sleep and Health (480 KB, PDF)
Sleep is essential and interacts with many bodily systems. Two biological processes regulate the duration, quality and timing of sleep and determine chronotype (one’s measurable degree of “morningness” or “eveningness”):
- circadian timing – a process that generates 24-hour bodily rhythms that define periods of sleepiness and wakefulness and schedule other physiological processes in line with Earth’s light-dark cycle. The body’s master clock in the brain synchronises with the outside world primarily through light, and with clocks in other cells in the body via hormonal and neuronal signals. Circadian rhythms are also affected by the timing of meals, physical activity and social cues.
- sleep-wake homeostasis – a process that increases (or decreases) the pressure to sleep with the time spent awake (or asleep).
Shift Work, Sleep and Health
Shift work – including night work and long working hours – is common to many sectors, with night workers comprising 12% of the UK workforce. Shift work can disrupt sleep and circadian timing, which can affect health and performance and increase the risk of accidents. Reducing its impact is a potential way to improve public health, health and safety in the workplace, and increase productivity.
Shift workers tend to have increased sleepiness during night shifts, and shorter and poorer quality sleep during the day. Chronic sleep and circadian disruptions can result in a diagnosis of shift work sleep disorder, which affects 10–30% of shift workers. Sleep and circadian disruptions are associated with a range of short- and long-term health effects in shift workers.
Shift work is common in healthcare, manufacturing, transport, communications, emergency services, security, entertainment and service industries, among others.
Key areas for policy discussed in the briefing include:
- NHS staff are at high risk of sleep and circadian disruption, and there is evidence showing that fatigue is linked to increased risk of medical errors with consequences for patient safety.
- Shift-work related fatigue has been implicated in several serious workplace accidents. For example, fatigue has been linked to 21% of UK rail incidents. Fatigue risk management systems are commonly used in some sectors to minimise shift work-related fatigue and accidents at work, in addition to regulations defining appropriate working conditions and hours.
- There is active research on interventions that could minimise shift work-related sleep problems.
- There are calls from a range of stakeholders for improved education and awareness among the general public and by employers about the health effects of shift work, and the interventions that can be adopted to manage them.
Key Points in the POSTnote:
- Shift work (working outside regular daytime hours) is common in many safety-critical and other sectors, including transport and healthcare.
- Shift work can disrupt sleep and circadian timing, essential biological processes that affect many aspects of physical and mental health and performance.
- Shift work is linked with an increased risk of sleep problems, occupational and driving accidents, and long-term health conditions.
POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:
- Professor Derk-Jan Dijk, University of Surrey *
- Dr Michael Farquhar, Guy’s and St Thomas’ NHS Foundation Trust *
- Dr Hugh Selsick, The Royal London Hospital for Integrated Medicine/University College London Hospitals *
- Professor Franco Cappuccio, University of Warwick *
- Dr Michelle Miller, University of Warwick *
- Professor Jim Horne, Loughborough University *
- Professor Niro Siriwardena, University of Lincoln *
- Professor Graham Law, University of Lincoln *
- Professor John Stradling, University of Oxford, OSA Partnership Group *
- Gillian Gibbons, OSA Partnership Group *
- Professor Paul Montgomery, University of Birmingham *
- Dr Nicole Tang, University of Warwick *
- Dr Simon Kyle, University of Oxford *
- Professor Colin Espie, University of Oxford and Big Health *
- Dr Chris Miller, Big Health and University of Oxford *
- Dr Richard Stott, Big Health and King’s College London *
- Dr Christopher-James Harvey, University of Oxford *
- Dr Katharina Wulff, University of Oxford *
- Professor Matt Jones, University of Bristol
- Dr Pete Blair, University of Bristol
- Professor Peter Fleming, University of Bristol
- Dr Donna Littlewood, University of Manchester
- Dr Rob Hunter, British Airline Pilots’ Association *
- Anh Tran, Public Health England *
- Health and Safety Executive *
- Department of Health and Social Care *
- Mary Higgs, Department for Work and Pensions *
- Anna Jones, Department for Education *
- Department for Transport
- Richard Allday, Unite the Union
- Marco Hafner, RAND Europe
- Petr Nalevka, Urbandroid *
- Jiri Richter, Urbandroid *
- Helen Bogan, NHS Employers
- Lisa Artis, The Sleep Council
- Laurie Heselden, Trades Union Congress
- Hugh Robertson, Trades Union Congress
- Caitlin Turner, Royal Society of Public Health *
- Sleep Apnoea Trust Association *
- Kevin Clinton, Royal Society for the Prevention of Accidents *
- Dr Josie Cheetham, Welsh Junior Doctors Committee, British Medical Association *
- Robert Wilson, British Medical Association *
- Kim Sunley, Royal College of Nursing *
- Dr Tim Quinnell, British Sleep Society and Papworth Hospital Foundation NHS Trust*
- Professor Jason Ellis, British Sleep Society Research Committee and Northumbria University *
- British Lung Foundation
- Caroline Heron, AQNB Productions
*denotes people who acted as external reviewers of the briefing.
Documents to download
Shift Work, Sleep and Health (480 KB, PDF)
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