Advantages of fixed summer time
There is no saying whether fixed summer time or fixed winter time is better or worse. Both have their advantages and disadvantages.
In the European Commission survey, most wanted to keep summer time all year round. Leaving work in the middle of winter and enjoying an hour or soof sunlight would be the main point in favour of this kind of change.
Moreover, with the summer time arrangement there are fewer traffic accidents, as the return home, when we are tired, is done in sunlight.
Spain would not only benefit from maintaining a single time arrangement throughout the year, but ought to also adopt the relevant geographical time zone, namely, that of the Greenwich meridian. This would put us on the same time as London and the Canary Islands… and the stock phrase "one hour behind in the Canary Islands" would disappear forever from news broadcasts.
Disadvantages of fixed summer time
However, in the particular case of Spain, some autonomous communities would be affected if the summer time arrangement were fixed. For example in Galicia it would not get light until 9:30 am. This would be difficult for the human body to deal with, as it is used to doing daily activities in the hours of sunlight.
It should be noted that if it gets dark later our rest time would also be affected. More hours of sunshine can be enjoyed, but the time when we go off to sleep would be delayed. Moreover, the time when we wake up to go to school or work would be the same, so we would be more tired and performance and productivity could decline.