World Sleep Day 2024 is celebrated on 15 March and this year’s theme is “Sleep Equity for Global Health”. Sleep is vital for good health, but there are significant disparities in sleep quality across different groups of people around the world, creating health challenges and worsening health inequalities.
In recognition of World Sleep Day, Dr Rachel Sharman, Senior Postdoctoral Researcher in Sleep Medicine in the Oxford Health Biomedical Research Centre (OH BRC) Better Sleep Theme explains the impact clock changes have on our sleep.
Clock changing for summer has taken place in Britain since 1916 to make better use of daylight, save energy and get people outside. The clocks go forward every year in March and go back again in October, returning to Greenwich Mean Time.
As spring approaches, so does the annual tradition of adjusting our clocks forward by an hour in the UK. Although this winter ritual signifies the onset of longer days and warmer weather, it can also have a subtle but significant impact on our sleep patterns.
Dr Sharman says: “The transition to daylight saving time occurs on the last Sunday in March. On this day, at 1am, clocks spring forward to 2am. This relatively small jump can, for some, mean that they lose an hour of sleep. Whilst this single-hour loss may seem like a small adjustment, its effects can be widespread.
“One of the most immediate consequences of the spring clock change is the disruption of our circadian rhythm. Our internal body clock runs to an approximate 24-hour cycle and allows us to anticipate environmental demands, such as when food would be available and regulates a sleep-wake cycle. Our body clocks are not exactly 24 hours in length, so the system relies on “zeitgebers” or time givers, a cue that influences the body’s circadian rhythm to help synchronise our internal clock to the external environment. For example, the dimming of light to signify the end of daytime.
“Typically, our exposure to light aligns with our social and occupational needs, known as our social clock. However, when our exposure to daylight doesn’t match our societal schedule, it leads to a mismatch between our internal clock and that of the environment. When we suddenly advance the clock for the clock change, it can take days, if not weeks, for our bodies to synchronise with this new schedule and reduce the misalignment. A common experience felt by those taking international trips and experiencing jet lag.
“For some, this shift can lead to disrupted sleep patterns and sleep deprivation leaving us feeling groggy, irritable, and less focused during the day. Studies have shown that this sleep deficit can impair cognitive function, decrease productivity, and even impact mood and mental health.
“Studies have revealed that there is a rise in accidents on the roads and in workplaces following the spring clock change. It is believed that the change in sleep patterns can negatively impact reaction times and decision-making abilities, thereby increasing the likelihood of accidents.
“Moreover, the spring clock change can exacerbate existing sleep problems, such as insomnia. Individuals who struggle to maintain a regular sleep schedule may find it challenging to adjust to sudden changes. For example, adolescents already experience a delay in their circadian timing at puberty, likely caused by hormonal changes. This delay is thought to be from 1 to3 hours, meaning a 9am lesson could feel like a 6am lesson for a teenager. The spring clock change would add an hour to this delay, potentially impacting academic performance in the short term.
“Many policymakers and individuals are considering whether clock changes are necessary. Several countries have abolished Daylight Saving Time (DST) entirely and the European Union has been discussing the elimination of the seasonal clock change since 2018. In 2019, the European Parliament voted to abolish the biannual clock changes by 2021. However, the decision was postponed, and member states were given the option to decide whether to remain on permanent summertime – (Daylight Saving Time) or wintertime standard time). The American Academy of Sleep Medicine released a position statement on 1 January 2024 in favour of permanent standard time.
However, all may not be as simple as cancelling the clock change. If the United Kingdom were to cancel the clock change associated with DST, it would have implications for the distribution of natural light throughout the year. This change in the distribution of light would have a greater impact on those in a more northern latitude, such as north Scotland, and so there are several unique challenges and considerations regarding daylight hours, regardless of the clock change.
“Fortunately, there are strategies we can employ to mitigate the impact of the spring clock change on our sleep:
Gradual Adjustment: Start shifting your bedtime and waking time by 15 minutes each day in the days leading up to the clock change to ease the transition.
Prioritise Sleep Hygiene: Maintain a consistent sleep schedule, create a relaxing bedtime routine and ensure your sleep environment is conducive to restful sleep.
Limit Stimulants: Minimise consumption of caffeine and alcohol, especially in the hours leading up to bedtime, as they can disrupt sleep patterns.
Maximise Light Exposure: Get plenty of natural sunlight during the day, particularly in the morning, to help regulate your circadian rhythm and signal wakefulness.
Be Patient and Flexible: Recognise that it may take time for your body to adjust to the new schedule and be gentle with yourself during this transition period.”
To find out more about the Oxford Health Biomedical Research Centre’s (OH BRC) research on sleep, see the OH BRC Better Sleep Theme webpage.
