This weekend, coinciding with the last Sunday in October, it's time to turn the clocks back. As is usual at this time of year, in the early hours of Saturday the 28th to Sunday the 29th, we will go from summer time to winter time. At three it will be two o'clock - except in the Canary Islands, where at two it will be one o'clock -, meaning that Sunday will exceptionally have 25 hours instead of the usual 24.
The time change means that it dawns and dusks earlier. It mainly affects the afternoons since the sun sets an hour earlier. As the days progress, the days will get shorter until they reach the winter solstice, December 21, which marks the shortest day of the year. From then on, sunlight will increase.
From the moment we turn back or forward (in March) the hands of the clock, a time imbalance occurs in our body that not only affects sleep, but also other physiological activities, such as appetite or cognitive processes. "This is a sudden desynchronization of our circadian rhythm - the biological rhythm whose main stimulus is sunlight - from the social clock marked by the time of the region where we are," explains Dr. Ana Fernández Arcos, a neurologist specialized in Sleep disorders.
This sudden alteration in our body clocks can have an impact on the performance of the different daily activities that we carry out. As far as driving a vehicle is concerned, the impact is much less now, with the change from summer to winter time, than when we advance the clocks in spring.
“The autumn transition causes more exposure to light during the morning and less in the evening. This will cause our sleep-wake cycle to adjust more quickly, since we start sleeping for an hour more. People who drive at night could be more affected by having less exposure to light and the need to sleep earlier, and could have a greater risk of drowsiness while driving,” says the neurologist.
In any case, adaptation to the time change now, in autumn, is much faster than in spring. “It can take months to adapt to the time change that occurs in spring while the change that will occur in the coming days is usually faster, around a week. It will also depend on the person. For example, those who have a more morning chronotype, who go to bed and get up early, adapt better to daylight saving time.”
According to the postdoctoral researcher in Barcelona Beta Brain Research/Fundació Pasqual Maragall, the change to daylight saving time affects drivers more than the adjustment that we are going to experience this weekend. “As the clock goes forward, the duration of sleep decreases by one hour. This entails some daytime consequences such as drowsiness, slower reaction speed and lower attention span.”
He also emphasizes that in March, when dawn suddenly rises later, “there is less morning light, which is a factor that helps us be more awake and alert.” Likewise, he adds that various studies have observed an increase of up to 6% in accidents during the time change period in spring.
Regarding age groups, the specialist in Sleep Disorders assures that elderly people are the ones who are most affected when we turn back the hands of the clock. “They have less need for sleep than children and young people. The fact of having an extra hour can affect them, waking up much earlier than they would like.” On the other hand, in the month of March, when we turn the time forward on our clocks, the main victims tend to be teenagers because they have a tendency to go to sleep and wake up later.
When driving, neurologist Fernández Arcos advises people with difficulties adjusting their sleep cycles to maintain a regular schedule, including weekends, and sleep between 7 and 9 hours a day. She also recommends doing physical activity (exercise or walking) outdoors in the morning, as she states that “sunlight helps adjust the circadian rhythm and reduce fatigue that can appear during the time transition.”
And one last note, which directly affects those people who have sleeping problems. “Returning to winter time can be an opportunity to improve habits and achieve sleep time more appropriate to your needs,” concludes Dr. Ana Fernández, who is also coordinator of the Sleep and Wakefulness Disorders Study Group. the Spanish Society of Neurology.
