I used Omni-8, intensity range between four and five. Hours ranged from 2-6 hours six days a week, the majority of the time was five hours. Sometimes I would go longer but usually after five hours the headband would start to bother me. I have curly/coily hair which is more fragile so I get more shedding and breakage than someone with straight hair. Anyway, I noticed the difference at about week three. There may have been improvement before week three but not enough for me to notice.
No negative side effects.