There are a few possible explanations for why your blinds might be bending. It could be that the weight of the blinds is causing them to sag in the middle, or it could be that the heat from the sun is causing the blinds to warp. If you think that the problem is due to the weight of the blinds, you can try adjusting the tension on the cords so that they're tighter. If you think that the problem is due to heat, you can try moving the blinds so that they're not in direct sunlight. Lastly, it's possible that your blinds are just getting old and need to be replaced.