Effect of UV radiation on scalp and hair growth

Abstract

Scalp, even covered by hair, is altered by both UVA and UVB irradiations. Melatonin is a light-influenced mediator released by the pituitary gland that affects hair biology. The speckled subclinical perifollicular melanoderma probably results from the release of melanocortin at the hair follicle openings at the skin surface. The mottled subclinical interfollicular melanoderma is related to cumulative Sun exposures. Ultraviolet (UV) exposure can lead to early teloptosis (exogen phase) and to the hair eclipse phenomenon (lag phase between two successive hair cycles). The events are responsible for the actinic telogen effluvium. Androgenetic alopecia appears to be adversely influenced by UV exposures. Actinic field carcinogenesis of the scalp is responsible for most of the actinic keratoses and squamous cell carcinomas of the scalp. The hair shaft structure and color are directly altered by UV radiations. © 2010 Springer-Verlag Berlin Heidelberg.