In my mind, the hair dryer uses too much electricty, more than it's worth. The average hair dryer uses between 1200 and 1800 watts. Some even use more! If you use the hairdryer for 10 minutes every morning, the cost can really add up.
Plus, I would think your hair is healthier without the forced drying. Of course, some may disagree, especially if you have longer hair. I guess in that case I'm envious since I'm rapidly losing mine!
