I like to swim laps as it is not only healthy, but a sort of meditation. Most days, I will swim a mile or so late (because that's when the pool is open). I noticed that as I do this every day, I tend to need more sleep. Normally, I sleep around 7-7.5 hours but after working out like this every day for 3-4+ days, it seems like I need 8-9 to just function. Is this normal? I thought working out was supposed to give you energy. Also, I do have mild insomnia (part of the reason I started swimming in the first place).

Note: I realize there are simillar posts, like this, but I haven't found one specific to this problem.

Thank you.