I notice the same thing, that energy is high beginning in the spring. I think my girls' young age keeps their main focus on nature, so it's natural that the ability to be outside comfortably charges them up on every level. But our "down time" is more like "grouchy time" but it could be the age of our family.
We also have a few things to prepare for starting in the spring that energizes them: 4-H projects and preparations for fair, the excitement of camping at the beach, and now Girl Scout camp.
In the fall and early winter, the holidays keep them busy physically and mentally. Gymnastics starts back up for us and our week settles in. After Christmas things start getting a bit dull, even with the prospect of a birthday approaching. The weather starts to wear on us and tempers flare more than usual.
My 7yo has taken to spending a lot of time with her nature books, but my 9yo hasn't found her quiet pastime yet. She has snippets but hasn't really "settled in" I guess. By February after birthdays the mood turns south and boredom has taken root in a bad way. I was thankful this year to have cookie season to prepare for and then chicks to raise. It could be that all these external activities keeps them from finding their groove at home amongst their books and things, but I'll take whatever I can get that gets me through January and February without strangling them (or strangling each other).
It is "backwards", or school is backward. Kids never get a chance to be with their school gardens over summer unless they volunteer. But I'm glad kids have a chance at their freedom in the summer. For schoolkids, this is their chance to immerse themselves in the kind of life that homeschoolers get (if schedules would leave them alone). I only wish they could enjoy more of May, June and September in our gorgeous weather. I feel so sorry for them on those gloriously sunny and mild days when the gardens are full and the breeze is balmy.
Speaking of, another gorgeous day in store for us....
"She is a mermaid, but approach her with caution. Her mind swims at a depth most would drown in."