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Spring is suddenly here and with it comes British Summertime when the clocks move forward on 25th March. This gives us one hour less time in bed on Sunday morning and may also bring disrupted sleep to some people in the week following the change. So read on to find out why and what you can do to help you adjust.
British Summertime was introduced in the UK by the government in 1916 to make the most of the daylight hours during the summer. This was to save money and fuel during the First World War and to increase productivity in the evenings.
Many welcome the lighter evenings that come with the spring clock change but research shows that sleep can be disrupted by up to a week following the shift in time. The Great British Sleep Survey involving 21,000 adults in the UK found that sleep quality falls by an average of 8% following the change with 12% also reporting low energy and low productivity and 11% reporting a negative impact on their relationships.
Why is our sleep affected by the clock change?
The master circadian clock is found in an area of the brain called the hypothalamus. Using light information from the eyes, this clock sets the internal biological time to the local day-night cycle so that biological processes such as eating and sleeping occur at appropriate times. All cells in the body have been found to contain a molecular clock and these are synchronised by the master clock in the brain. So for example, heart cells and liver cells all have internal molecular clocks aligned to the local day-night cycle. When we experience a change in the local time, we end up sleeping and eating at times that are slightly out of sync with the internal biological clock and this can have short-term negative consequences until we have fully adjusted.
The effect of changing to British Summertime on sleep and fatigue reflects symptoms of jet-lag when people travel across time zones. Jet-lag occurs because your body’s circadian rhythm or biological clock is out of sync with the local time zone. Effectively, moving the clock forward is the equivalent of flying across a one hour time zone. Our internal circadian clock does not adjust rapidly to these changes in local time and it can take a number of days for it to resynchronise. This can lead to problems with sleep and energy levels, appetite and digestion and other symptoms. Once you have adjusted to the time change, these problems should return to normal.
However, some people may be living with these problems on a more permanent basis if their internal circadian clock is set slightly earlier or later than the average. A proportion of the population are ‘owls’ or ‘larks’ and this is partly determined by genetics. Owls’ internal clocks mean they prefer to go to bed or get up later and these times don’t fit with social schedules of work or school. This can lead to what is referred to as ‘social-jetlag.’ So an owl might not go to bed until after midnight in the weekdays but they have to get up for work or school at say 7am which means cutting sleep short if their natural wake up time is closer to 9am. However, at the weekend they might revert to their natural sleeping times of say 1am to 9am, plus sleep a bit more to pay back the accumulated sleep debt of the week. This consistent change in sleeping pattern over the course of a week may disrupt the circadian clock in the long term and is associated with reduced sleep quality and psychological wellbeing and an increased use of caffeine, nicotine and alcohol.
Interestingly, reports of social jetlag spike after the spring clock change as we are getting up an hour earlier than we are used to for work in the week following the move but our bodies haven’t adjusted quick enough to get to sleep an hour earlier . Owls may be more affected by the spring clock change as it means their internal biological clock temporarily becomes more misaligned with the demands of social time.
What you can do to help
Since your circadian clock is regulated by light from your environment, get outside in the natural daylight as soon as possible after you wake up. This will help you adjust more quickly to either a clock change or to a change in time zone. So even if you feel tired, try to get outside for at least half an hour in the morning. Not only will this make you feel more awake and alert but it should help you to sleep better on the Sunday night and reduce that groggy feeling on Monday morning.
Although you may be tempted, try to avoid a lie in on the Sunday morning. This will just make Monday morning even worse. The best advice for your sleep is to maintain consistent bedtimes and rise times seven days a week, even at the weekends. This will help to regulate your circadian clock.
Adjust slowly to the clock change the week before. Plan to go to be 15 minutes earlier than your usual time on the Wednesday before the clock change and get up 15 minutes earlier on the Thursday. Adjust your bedtime and rise time by 15 minutes each day until you get to Sunday morning. This will reduce the impact of the change on Monday morning.
And remember if your sleep is disrupted temporarily try not to worry about it as this can make sleep problems worse.