One of the best ways to take care of your skin is to remove the foundation.  Essentially you want a light foundation to wear during the day so it doesn’t clog your pores and otherwise anyway, and if it has a sunscreen, that’s not a bad thing either, especially during the day.  Foundation should not be banned all together.   But as you sleep and as you exercise, you don’t need to wear foundation or other makeup for that matter.  It can have chemicals that irritate your skin anyway or clog pores when you don’t choose the right one.  But frankly, when you sleep with it on, your pores are opening up to try to repair the skin and otherwise, and they end up absorbing more of those bad things.  And while exercising, obviously you are sweating more and otherwise anyway.  You are producing more oil, and all of this can cause breakouts which can lead to acne scars and it can also lead to future aging problems among other skin problems in general.  So all in all, it is best to avoid harsh foundations all together.  But avoid foundation all together when it comes to certain times such as exercise or sleep.  It’s simply not necessary or prudent for that matter.