British Summer Time

British Summer Time (BST) is the UK’s seasonal clock change that moves time one hour ahead of Greenwich Mean Time (GMT) to extend evening daylight from late March to late October (this is sometimes referred to as ‘daylight saving’).

The UK moves clocks forward to BST at 1 am on the last Sunday in March to shift an hour of daylight from morning to evening. It moves clocks back to GMT at 2 am on the last Sunday in October to shift an hour of daylight back from evening to morning.

Although there have been calls to make changes to these daylight-saving measures in the past, and the issue continues to be raised in Parliament, the government has confirmed that it has no plans to make any changes to these arrangements.

In the UK, public opinion on clock changes is split. A 2024 poll found that 46% were in favour of British Summer Time and that 42% were in favour of ending it.

Proposals to change clock times

There have been multiple legislative attempts to make changes to the UK’s daylight-saving measures. A series of private members’ bills from the 1990s onwards have sought to introduce year-round or extended summer time, either on a permanent or experimental basis.

The most recent attempt was the Daylight Saving Bill 2010-11, introduced by Rebecca Harris MP (Con). It would have required the government to undertake a cost-benefit analysis of moving the clocks forward and to run a trial clock change.

Evidence of the effects of clock changes

The government’s position is that there is no compelling case for making changes to the UK’s current daylight-saving arrangements.

A 2012 review commissioned by the coalition government concluded that more research evidence would be needed to conduct a cost-benefit analysis of proposed changes to daylight savings. The report highlighted uncertainty about how the public would respond to any change.

In February 2020, the House of Lords European Union Committee reached a similar conclusion, noting a lack of contemporary research and public consultation. The committee’s inquiry, Clock changes: is it time for change? was a response to a 2018 proposal to end clock changes in the EU. The EU proposal was never implemented.

The existing evidence base on the effects of daylight-saving measures is mixed.

Energy use

Evidence on energy use suggests that the impact of clock changes on energy demand is unclear. Research from Turkey, where clock changes ended in 2016, found no overall effect on electricity use. However, it did find a change in use patterns that favoured clean energy sources and so lowered carbon emissions.

Road safety

Evidence from the British Standard Time experiment in the late 1960s suggested that moving to permanent summer time (GMT + 1 hour) could reduce fatal and serious road accidents. A 2009 Department for Transport report estimated that introducing double summer time (GMT + 2 hours) could save around 80 lives each year. However, more recent evidence on road safety is inconsistent, and does not strongly favour any particular daylight-saving measures, or none.

Health

The evidence on the impact of clock changes on health is also mixed and generally focuses on the short term effects of transitions, which are generally found to have negative effects. A large study of patients in the US found that clock changes affected patterns of mortality over the year, including a drop in deaths following the autumn clock changes, but no overall effect on mortality rates.

A 2024 review of research from different countries found that there was a small increased risk of a heart attack following the spring transition, when the clocks move forward. However, the reviewers found that individual studies reported very different effects.

A 2025 English study reported fewer recorded health problems in the week following the clocks going back, including cardiovascular events, mental health problems and sleep disorders. The researchers in this case noted that there could be a lag between symptoms developing and a health problem being recorded.

In 2024, The British Sleep Society published a position statement supporting an end to clock changes, arguing that they impair circadian rhythms and sleep health, especially after the spring transition.