But, to relax and take a break from your studies, have you considered doing some sport? It might be better than the DS.

Superlegtesta

I've recently picked up archery, GREAT sport for just going out for an hour here and there to the range, shoot some arrows, then come back home. Even better if you live in the country, but most of us dont. Look online for a place to shoot before you buy, I found a free range to shoot at then bought a used compound bow and arrows for a hundred bucks. Cheaper than a DS without a game!