The extreme heat from hair-dryers (and from curling irons) causes the water under the cuticles (the outermost layer of the hair) to form bubbles that stress and break the hair.
The tiles that cover the hair dislodge and your hair handles water like an unroofed house. You'll get those dreaded split ends and your collie's hair will outshine yours. It's best to blot hair dry with towel and then use low heat if you use a dryer. Your hair is actually most vulnerable when it's wet, and you should treat your hair almost like you would a silk blouse - don't iron it or heat it up to extremes. Also, it's smart to use a brush with smooth or rounded teeth or bristles, which will massage the hair and scalp without damaging them.
See, using a hair dryer too much can cause damage to your hair by drying it out and breaking it. To limit how much, you use a blow dryer, let your hair air dry partially before you use the hair dryer. This can even give your hair more body. (Don't vigorously towel dry wet hair, as this can cause wet hair to break). If you don't need the blow dryer every day be it one of the top hair dryers, don't use it.
Today's commercially available hair dryers are relatively safe to use on one's hair. However, any mechanical manipulation of the hair does introduce risk for damage to the hair.
A few simple guidelines can help minimize the likelihood of damaging your hair through the use of a hair dryer.
Hair can suffer plenty of damage over time as a result of straightening hair, hair coloring, hair highlights and other treatments. The loss of pigment as we age also causes gray hair, and it may appear sooner than you'd expect. Dandruff and thinning hair are other common problems, along with frizzy hair and oily hair.