There are around 8.7 million shift workers in the UK, and a recent Guardian article explores the challenges faced by working against our natural circadian rhythms, drawing on research from several experts in the field of sleep. Professor Steven Lockley (visiting professor at the Surrey Sleep Research Centre, University of Surrey) explains that humans have evolved to be awake during the day and asleep at night and that this is mainly controlled by the suprachiasmatic nucleus in the hypothalamus. When we work shifts, particularly night shifts, we're forcing our bodies to function against what our endogenous pacemaker is programmed to do.

The health implications are substantial and well-documented. Shift workers face elevated risks of heart disease, hypertension, obesity, type 2 diabetes, stroke, depression, anxiety, and certain cancers. The World Health Organisation has classified shift work as 'probably carcinogenic'. Beyond these chronic conditions, there are immediate safety concerns, with workplace injury risk increasing by 36% after four consecutive night shifts, and medical errors becoming more common during night shifts. Shift work also significantly impacts relationships and family life; one study found divorce and separation were six times more likely for men working night shifts in the first five years of marriage. Professor Sian Moore from Anglia Ruskin University surveyed workers from five unions and found that even those who said night shifts fitted their lives reported 'appalling' sleep.

Professor Russell Foster highlights that 97% of people cannot fully adapt to working nights, even natural 'owls' with evening chronotypes. This is because our circadian rhythms are primarily reset by light as an exogenous zeitgeber, and most shift workers are exposed to contradictory light cues on their days off, preventing true adaptation. Even oil rig workers, who work under bright lights at night and sleep in dark, windowless rooms during the day, only begin to adjust towards the end of a two-week stint.

The article discusses various interventions that can help reduce these problems. Lockley emphasises that more thought should be given to rota patterns, with employees' night shifts minimised and transitions managed carefully. Going from day to evening to nights is better, and 'quick returns' (where someone works an evening shift then a morning shift the next day) should be avoided. When he applied these rules to resident doctor schedules at a healthcare trust, there was a 30% fall in serious medical errors. Lighting in the workplace is another key factor; cooler, bluish light makes the brain think it's daytime, promoting alertness on duty. Individual strategies include maintaining healthy lifestyles, strategic caffeine use (Lockley recommends about 21mg per hour for a 70kg person, roughly half a weak tea or coffee, stopping six hours before planned sleep), short naps of 10-20 minutes before shifts, and proper sleep hygiene.

Reference: The perfect way to look after your health if you work shifts | Health | The Guardian (accessed 11.2.26)

ANSWER THE FOLLOWING QUESTIONS!

1. Explain how shiftwork disrupts our circadian rhythm.

2. Using your knowledge of exogenous zeitgebers, explain why the article recommends cooler, bluish light in workplaces for night shift workers.

3. The article mentions that Professor Foster found that 97% of people cannot adapt to working nights. Suggest why even natural ‘owls’ (those who feel more alert late at night and prefer to get up later) struggle to fully adapt.

4. The article mentions a study that found divorce and separation were six times more likely for men working night shifts in the first five years of marriage.

Suggest one limitation of using correlational research to investigate the relationship between night shift work and relationship breakdown.

5. Identify one advantage and one disadvantage of using self-report methods (questionnaires) to investigate sleep quality in shift workers.