Younger and elder humans have less-flexible biological rhythms and struggle more to adapt to change, says SES chronobiology coordinator Javier Albares.
“There’s a lack of concordance between the biological clock and the social clock, which is what changes twice a year, so our bodies need a few days to adjust,” Albares, who is also medical director of Barcelona’s Teknon Clinic sleep unit, explains.
“Whilst adults adapt within about three or four days, older people may have more problems – sleeping too early or getting up too early for a week or two.
“This is in spite of the fact the autumn clock change affects health less than when the clocks go forward in spring, because we gain an hour’s sleep.”
Repercussions can include either tiredness or insomnia, mood changes because of the extra hours of darkness, and the digestive system falling out of synch.
Albares recommends those who have the most trouble adjusting undertake extra physical activity before nightfall to help them sleep, and expose themselves to extra light if they feel tired before they should do socially – even artificial light sources – or take a short siesta of 15 to 20 minutes to make them feel the need to go to bed later.
Dr Alejandro Guillén-Riquelme of Granada University says the effects are similar to jet-lag and assures those affected they ‘have no need to obsess about it’ but should be kind to themselves ‘until it passes naturally’.
Time zone debate continues in Spain
The debate rages on about Spain’s time zone – geographically, it sits in the Greenwich Mean Time strip and the Meridian Line runs through the town of El Verger on the northern coast of the province of Alicante, but only the Canary Islands are on GMT in winter and BST (British Summer Time) from late March.
The north-western region of Galicia wants to be on UK time, in line with Portugal which is directly due south of it, whilst the Balearic Islands – which is in daylight an hour before Galicia on summer mornings and for an hour after Galicia gets dark in the evenings – wants to go forward an extra hour, putting it on Greek and Turkish time, since the extra sun benefits tourists and commuters.
Those in favour of putting Spain back on GMT say it would mean the country is less sleep-deprived, as working hours would end earlier, people would eat their evening meal at around 19.00 rather than 22.00, and go to bed earlier, but physics experts say populations adapt to their time zones and that Spain’s late functioning is unique, given that Belgium and France are also on the wrong times and their hours are similar to those of the UK.
The jury is out as to whether Spain’s incorrect time zone is because of Franco wanting to align with his Nazi Germany and Fascist Italy allies during World War II, or whether it was French president General de Gaulle who opted for CET as part of the post-war peace alliance and Spain followed suit.
Daylight vs ‘social cycle’
Research on circadian rhythms has shown that changes in light sources can affect the biological clock – Siffre (1975) spent six months in a cave with only artificial light, and believed he had only been there for four months, as his circadian rhythm had extended to between 25 and 27 hours.
Experiments involving shining light on the back of sleeping volunteers’ knees led to their waking up, showing that light does not have to enter via the eyes to trigger the sleep-wake cycle.
But research on Arctic communities showed that their ‘natural’ circadian rhythm ranged from 22 to 27 hours, even in mid-winter when they had barely an hour of daylight, and in mid-summer where it does not get dark.