The Consequence of Daylight Savings

Jet lag can be categorised into two main types: traditional jet lag (caused by travel across time zones) and social jet lag (caused by differences between our biological clock and social schedule). Both types disrupt the body's internal circadian rhythm but arise from different causes.

This weekend, we will experience another form of jet lag as we will be part of a seasonal clock change. On 27 October, the clocks will turn back by one hour at 2 a.m. as daylight saving time (DST) ends. This change can affect our circadian rhythm, similar to jet lag, as it alters the time we wake up, sleep, and conduct daily activities. Although the shift seems minor, this one-hour difference can lead to feelings of fatigue, disrupted sleep, and difficulty concentrating, especially for those with sensitive body clocks.

The circadian rhythm is closely tied to the 24-hour day and responsible for regulating sleep-wake cycles, hormone release, body temperature, and other daily biological processes. When you travel to a different time zone, shift your sleep-wake schedule, or go through DST, your body remains synchronised with your original time zone for a while, causing a misalignment with the local time. This misalignment causes jet lag symptoms, such as fatigue, insomnia, digestive issues, and difficulty concentrating.

What impact does DST have on us in general?

A UK-based study by the Sleep Council found that about 60% of people felt the clock change negatively impacted their sleep, leading to fatigue and difficulty concentrating in the days following the transition.

Research has shown increased mood disturbances, such as depression, following the autumn clock change when daylight hours shorten abruptly. Seasonal Affective Disorder (SAD) is more prevalent during the transition to the winter months, exacerbated by the earlier onset of darkness after the clocks go back. The Mental Health Foundation noted that around 5% of the UK population suffers from SAD, with many more experiencing milder seasonal mood swings.

One of the most apparent effects of DST in the UK is the rise in road accidents, particularly following the change in the autumn clock when there are fewer daylight hours in the evening. According to the Royal Society for the Prevention of Accidents (RoSPA), pedestrian deaths increase by 10% in the first few weeks after the clocks go back in autumn as more people commute in the dark.

In the days following the spring clock change, there is a noted increase in car accidents due to sleep deprivation and reduced alertness. RoSPA reports a 2-4% increase in road traffic accidents in the UK immediately after transitioning to DST in March.

Like global trends, the UK experiences a dip in workplace productivity following the DST change, particularly in the spring. Research by the Centre for Economics and Business Research (CEBR) estimated that productivity drops by around 3% in the week after the spring shift, primarily attributed to sleep disruption and fatigue. Employees are less alert and may spend more time distracted or taking longer breaks.

A study by Loughborough University found a small but significant rise in workplace accidents during the week following the springtime change, as workers were more likely to be fatigued and less focused.

A study published in the International Journal of Finance and Economics found that the UK stock market and other global markets tend to perform worse on the first trading day after the clocks are changed. This is likely due to the general disruption caused by sleep loss and the adjustment to the new schedule.

To put this into context, many people adjust their schedules by staying out late and sleeping on most weekends. This often takes 3-4 hours of adjustments and takes most of the working week to resolve.

This gives them a biological profile similar to a shift worker who isn't working to mitigate their phase shifts and is the equivalent of DST every week.

Although we considered some of the statistics and findings above, many people experience acute shifts most weekends, and simply staying up late and sleeping causes huge cardiovascular, mental, metabolic, and cellular health disruptions.

Reed Hastings, the co-founder and former CEO of Netflix, once made a notable statement regarding the company's biggest competitor. In a 2017 interview, he said:

"We actually compete with sleep. And we're winning!"

So, as we get drawn into another episode, what physiological impacts will we experience as a consequence? 

 The chart shared will outline the magnitude of those consequences across the four categories of cardiovascular, mental, metabolic, and cellular health.

The larger issue lies in something other than daylight savings, as we can adapt to this relatively quickly.

The biggest issues lie with shift work, frequent travel, and probably the most common: people merely adopting an irregular wake and sleep cycle at weekends.

One thing we constantly work on at HMN24 is picking a sixteen-hour wake and sleep window as the daily target. The more consistent that is, the more we mitigate the above.

What are you doing individually or within your workforce to educate employees on managing this simple yet hugely overlooked issue?