here is an interesting post on the subject by an MD who owns a chain of clinics in Texas and has been doing this (including some studies himself) for almost 10 years (since lasers first surfaced)
"jim1976 wrote:
I have 3 patches on my left shoulder that now have 50% more hair than the rest of my back, before the patch tests I had equal growth all over. explain that ! I can supply picks to prove.
Very simple to explain. And very easy to prove with hair counts. Pictures not required.
All the hair you are ever going to have is present at birth, but most of that hair is in a dormant stage. It is there but just not growing. It is well known that certain things can stimulate dormant hair to grow. Things like hormonal change, age (which is probably related to hormonal changes), and a host of other issues such as chemical burns and reactions to noxious stimuli.
So you come in for laser hair removal to treat an area that has 50 hairs. But there may be 300 hairs that are dormant. The laser hopefully kills all the hairs and shocks the other hairs into dormancy. This is why there is a period when there is no hair growing (it doesn’t always happen but is what is expected). Then after a period of time, the next crop of hairs start growing. But the energy in the laser can also stimulate hairs that would otherwise be dormant to also start growing.
So instead of having just fifty hairs growing, there may be a hundred. What does it mean, nothing. Other than it helps to make the laser hair removal more effective because now there are more active hairs growing that can be targeted and killed if the settings and the laser are effective.
This experience tends to go away after treatment number three or four, when a significant proportion of the hair is destroyed. But it can look weird and be unnerving in the beginning."
You can find this post here:
http://cosmeticenhancementsforum.com/forum/viewtopic.php?p=20285&highlight=#20285