With the clocks springing forward this month, Dr Sarah Gilchrist details the effect on our sleep
‘Spring forward’ refers to the practice of moving the clocks one hour ahead at the start of Daylight Savings Time, so that evenings have more daylight and mornings have less. It’s typically performed in the Spring, hence the phrase. This usually happens in the UK at one o’ clock in the morning on the third Saturday in March. Six months later, on the final Saturday in October, the reverse occurs when the UK reverts to Standard Time (fall back).
Historically, Daylight Saving Time was introduced in World War I in an effort to save energy by having lighter evenings. Through moving the clocks forward in Spring and back in Autumn, people were able to make better use of daylight and reduce the need for artificial lighting in the evenings. Subsequently, this has become seasonal practice aimed at maximising daylight hours and saving energy.
However, the biannual clock change between Daylight Saving Time and Standard Time is controversial and can be a major disruptor of sleep for some people. This is mainly due to the misalignment of their natural circadian rhythm, either forwards or backwards depending on the time of year. This misalignment can have a consequential effect on an individual’s productivity in the subsequent days following a clock change as they readjust following the loss or gain of one hour of sleep. As well as the adverse effects on sleep patterns (shortened sleep), it also has acute negative effects on health, including cardiovascular morbidity, alongside implications for performance and safety in the workplace and wider society1,2.
In particular, the darker mornings and loss of one hour’s sleep in the Spring mean it is harder to adjust to the clocks springing forward. Moving the clocks forward by one hour creates a ‘phase delay’ in the body’s innate natural circadian rhythm (biological clock) and it becomes at odds with the extrinsic environmental clock. Essentially, Daylight Saving Time squeezes sleep opportunity in both the morning and evening.
The body clock time remains close to 7am, aligned to natural solar time (the earth’s position in relation to the sun) but, on Daylight Saving Time, when clock time becomes 8am, the reliance on alarms to wake up becomes increased as body rhythms are delayed compared with social or work schedules. Although lighter evenings do give way for more opportunity for productivity, reduced morning and increased evening light exposure makes it harder for some people to fall asleep, with a consequential reduction in sleep opportunity.2
It can be argued that Daylight Saving Time is neither practical, nor beneficial, in modern industrialised societies. So much so, there is a move in contemporary cultures to remain on Standard Time (equivalent to Greenwich Mean Time, GMT). Interestingly only 70 out of 195 UN countries shift their time from international standard time; however, until such time shift seasonal changes are universally obsolete, societies will have to manage around the twice-yearly change.
During the spring forward clock change, it can be beneficial to recognise the negative effect bright light can have on sleep onset and make appropriate changes to help sleep, for example, eye masks, blackout blinds or curtains.
It may also be helpful in the preceding days before the spring forward clock change to move bedtime earlier by approximately 10 to 15 minutes, close curtains earlier, refrain from caffeine intake an hour earlier than normal, and reduce alcohol intake before bed. Similarly, when the clocks fall back in the Autumn, it could be useful to adjust a sleep schedule to later than normal by about 10 to 15 minutes in the days preceding the clock change. A regular sleep routine should be emphasised in readjusting to a clock change, in addition to getting plenty of natural daylight.
Don’t forget, the clocks spring forward on Sunday 30th March 2025.
Discover more about sleep in this FitPro blog post on poor sleep and sleep tips.
Dr Sarah Gilchrist
DR SARAH GILCHRIST FBASES spent over 20 years working in the high performance sport industry, latterly as a technical lead for the UK Sports Institute and senior physiologist with British Rowing. She provides consultancy on a range of performance areas, particularly relating to female sleep health, through Gilchrist Performance. Sarah is on the Advisory Board for the Sleep Charity, a fellow of the British Association of Sport and Exercise Sciences and is High Performance Sport accredited. She is an associate to The Active Women’s Clinic where she provides insight into female sleep health.
References
- Crawford MR, Winnebeck EC, von Schantz M, Gardani M, Miller MA, Revell V, Hare A, Horton CL, Durrant S and Steier J (2024), The British Sleep Society position statement on daylight saving time in the UK, Journal of Sleep Research, p.e14352.
- Johnson KG, Hale L, Johnson DA, Malow B (2024), Daylight saving time harms health and increases inequalities, British Medical Journal, 387, q2335. https://dx.doi.org/10.1136/BMJ.Q2335, accessed 4 March 2025.
