Page 42 - Blog Posts v1

A14 - Hair removal intervals – PART 1
Laser/IPL hair removal has been around, commercially, since the late 1990s. Many clinical studies have been carried out around the word looking at the optimum wavelength(s). fluences, pulsewidths etc. However, very little work has been done on the ‘best intervals between repeat sessions. As a direct consequence, the industry has adopted a rather haphazard approach to guestimating these intervals.
Many laser/IPL operators are trained to leave 4 or 6 or 8 or ‘whatever’ weeks between sessions, with virtually no explanation as to why!
So, I thought I’d put together a computer model to investigate this more thoroughly, using data that we do know.
Body Area
% Resting Hairs Telogen
% Growing Hair Anagen
30 70 10 52
2-4 500
Duration of Telogen (weeks)
Duration of Anagen (weeks)
Follicle Depth (mm)
Follicle Density (per cm2)
Beard (Chin)
35
65
6
8-20
1-2.5
500
Upper Lip
70 30 12 16 3.5-4.5 65 80 20 16 12 2-4 80
Data from Richards & Merhag.
Clinical studies in the 1960s and 70s investigated the growth rates of hair across the body in youngish, healthy individuals with no underlying medical issues. The table above shows what they found.
All hair goes through the standard anagen-catagen-telogen growth cycle. In most cases, the catagen phase lasts for around two weeks. So, the data above gives us a good idea of the rate at which hair grows and the percentages of hair in the anagen or telogen phase.
I constructed a model in Excel which describes these growth patterns over a year.
Arm Pits
70
30
12
16
3.5-5
70
Pubic Area
Arms
Legs & Thighs
80
20
20
16
2-4.5
60
Breast
70
30
12
8-12
2-4
65
Mike’s Blog Posts 42