Laser treatments have long been widely used by beauticians and dermatologists to smooth wrinkles; now research reveals why the treatments work. Susanna Dams, Ph.D., describes the process in her biomedical engineering doctoral dissertation for Eindhoven University of Technology. The principle of laser therapy is to introducing heat under the skin with precision.

Dams first tested the effect of heat on cell cultures, by giving them heat shocks of 113 degrees and 140 degrees Fahrenheit without a laser to exclude possible effects generated by the laser light. Next, she conducted similar tests on pieces of excised human skin. Finally, she heated pieces of skin with a laser.

The results showed that the heat shocks led to increased production of collagen—a crucial factor in natural skin rejuvenation that declines after the age of 25, causing wrinkles to form and skin to sag. The best rejuvenation effect in Dams’ research resulted from a heat shock of 113° F lasting eight to 10 seconds; her work further showed that just two seconds at the higher temperature damages skin cells.