I disagree with this. The summer time is much, much better for my mental health. I am stuck working all day and the time of day when I want to and can enjoy daylight is after 5pm. Hence, the summer hours are much better.
I can't speak for your psyche (and you may well be a naturally early riser), but we know that having to wake up earlier decreases a lot of people's sleep overall, and that is also not good for mental health.