Spain is already in the wrong time zone for standard time, and when DST hits, it's two hours off the time we really should have. It's unnatural for daylight to last until 22:00 or nearby in june and july in Spain's latitude. A bit more and we'd end up with some kind of midnight sun, like we were in the Arctic Circle. It's ridiculous.
I mean, it's usually so hot, and getting hotter every year, that you can only go outside somewhat comfortably after nightfall anyway, so I'd actually prefer if it got dark at 20:00 or earlier in the summer, as it should be. On the other hand, it's horribly demoralizing for me when it's almost 8:30 in the morning in mid-october and it's still so dark. Going back to standard time, like we did a few days ago, gives me a brief respite, but unfortunately dark mornings will soon return in a month or so.
That's probably even more of an issue for Spain, made even stranger by the fact that Portugal is in the "correct" timezone.
Much better than having sunset before 16:00.
Evidence-backed benefits of morning light exposure:
Advances the circadian clock, helping shift the body's biological night earlier. Randomized controlled study: https://pubmed.ncbi.nlm.nih.gov/24179293/
Promotes earlier sleep timing and may improve subjective sleep quality. Systematic review of 45 studies: https://pubmed.ncbi.nlm.nih.gov/30670164/
Improves alertness, attention, and reaction times, although average effects are small. 2025 systematic review and meta-analysis of 150 studies involving 5,401 participants (daytime light, not exclusively morning): https://doi.org/10.1080/15502724.2025.2493669
Helps treat seasonal depression (SAD). Systematic review and network meta-analysis of 17 randomized trials involving 773 patients: https://pubmed.ncbi.nlm.nih.gov/40629637/
Can improve outcomes in nonseasonal depression when bright-light therapy is added to treatment. 2024 meta-analysis of 11 randomized trials involving 858 patients: https://pubmed.ncbi.nlm.nih.gov/39356500/
Natural daylight exposure helps synchronize the biological clock with the solar day. Experimental research found that exposure to natural light-dark cycles advanced circadian timing compared with modern indoor lighting environments: https://pubmed.ncbi.nlm.nih.gov/23910656/