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][1], but I haven't found one specific to this problem.

Thank you.


  [1]: http://fitness.stackexchange.com/questions/11999/proper-sleeping-time-after-tough-workouts