Seasonal Affective Disorder has a summer and a winter version. I have been blessed with both and have had them for years.
My ability to sleep in June is almost non-existent. I have been able to deliver a major project early or on time for 10 consecutive years thanks to this.
Lack of sleep leads to all sorts of things, so it doesn’t surprise me that more serious issues happen to other people. I work on my sleep hygiene which helps, but I still get overstimulated with the continuous sun.
Once the days start shortening and it gets a little cooler I will feel much better.
Seems reasonable to say that this is a year round disorder....and always has been. The difference is...we’re all different. I live on 4 hrs of sleep year round..but have a nap about 2 for about 1/2-1 hour. done that since i was a kid. And my 3 younguns...we all took naps with mom.. I’m 79...and still have the same routine.