Experts urge U.K. to end daylight saving time, citing negative impacts on sleep and circadian health

By Priyanjana Pramanik, MSc.Reviewed by Lily Ramsey, LLMOct 25 2024

Sleep specialists highlight how twice-yearly clock changes disrupt circadian rhythms, recommending year-round standard time for better health and well-being.

Study: The British Sleep Society position statement on Daylight Saving Time in the UK. Image Credit: conzorb/Shutterstock.com

In a recent position statement published in the Journal of Sleep Research, experts presented evidence-based views on the effects that changing clocks during the spring and autumn has on sleep and circadian health.

They concluded that health is negatively impacted by enforced changes in clock time, particularly when moving one hour forward, and advocated for the abolition of this practice and reinstatement of Standard Time all year round.  

History of Daylight Saving Time

Daylight Saving Time (DST), also known as British Summer Time, shifts clocks forward by one year in late March and back again in late October. Before DST was implemented, the United Kingdom used Standard Time or Greenwich Mean Time (GMT) throughout the year, aligning with natural daylight patterns.

First introduced during World War I, DST was implemented again during World War II, with the current system of switching clocks twice yearly starting in 1972.

In 2018, the European Parliament considered abolishing the clock change, but no such steps have been taken in the UK. However, there are ongoing discussions around implementing either permanent DST or permanent Standard Time.

The British Standard Time is based on the Prime Meridien; since most of the UK is west of the Prime Meridien, this causes later sunrises and sunsets around the year.

Seasonal changes affect sunrise and sunset times more in the north of the country, which experiences particularly late sunrises in winter, reducing morning sunlight exposure before work and school.

Light and Circadian Rhythms

We have circadian rhythms or 24-hour body clocks that regulate key functions related to metabolism and sleep and are aligned by exposure to light. Morning light is specifically essential to keep our body clocks on track as it helps us wake naturally and sleep at the appropriate time.

However, evening light appears to delay sleep, making it more difficult to wake early, particularly for teenagers and people with early schedules.

More than electric light, sunlight is effective at aligning human body clocks. Thus, changes in light can disrupt circadian rhythms, causing sleep issues and other negative impacts on health.

DST does not provide more sunlight; rather, it shifts schedules to make greater use of evening light, reducing morning light. In summer, this change is not a significant issue because of earlier sunrises, but with permanent DST in winter, it could lead to less natural light in the mornings.

Permanent DST would result in darker mornings during winter, potentially worsening sleep problems and circadian misalignment.

International sleep experts argue against permanent DST due to its negative impact on sleep and health, but this hasn’t been addressed specifically for the UK.

The geographical context of the UK needs to be considered, especially with much later sunrises in winter under permanent DST.

The Case for Standard Time

Clock changes in March and October disrupt sleep and circadian rhythms. The spring shift results in sleep loss and short-term health issues like decreased productivity and safety risks.

The long-term effects of DST are harder to determine but may negatively impact sleep and health, especially in spring and autumn. DST can lead to late summer sunsets, which interferes with sleep due to light exposure near bedtime.

Implementing permanent DST would cause late winter sunrises and deprive morning sunlight, especially in northern and western UK.

Permanent DST would align UK time with locations further east, such as Western Poland, creating mismatches with local solar time. Specifically, most people in the country would need to wake up at least an hour ahead of their solar time.

Studies show living in a time zone misaligned with solar time harms sleep, circadian rhythms, and health. While permanent DST might give more evening light for a few weeks in spring and autumn, it sacrifices morning light, especially in winter.

However, permanent GMT would better align the UK’s clocks with solar time, reducing sleep and health disruptions. Sunsets in summer would still allow evening activities, and there would be more morning sunlight exposure in autumn and winter.

Any time zone changes in the UK should be coordinated with Ireland to avoid a time zone difference across the Irish border.

Conclusions

Based on current scientific evidence, the British Sleep Society and several other organizations issued a strong recommendation that permanent GMT is the best option for sleep and health.

They noted that the twice-yearly clock changes should be abolished and opposed the implementation of permanent DST due to health risks. Returning to permanent GMT across the country would reduce the potential dangers of affected circadian disturbances, sleep, and health.