French is tricky i see! You can say: ferme les yeux or ferme tes yeux, but not ferme-toi les yeux. This is incorrect. Why? It looks like because it is a very short and simple action. Close your eyes. You can say brosse tes dents, or brosse toi les dents but not brosse les dents. Here because it is an action you do for yourself, so you must use a reflexive.