Light energy can heat the infants by radiation
without changing the temprature of the surrounding air.
The authors believe that increase in body temperature is
a function of increase of irradiance rather than the type
of the light source, because LED phototherapy with low
irradiances did not cause significant hyperthermia similar
to conventional phototherapy with blue fluorescent
light. Alternatively hyperthermia might be related to
release of pyrogenic cytokines such as tumor necrosis
factor alpha (TNF-α), interleukin (IL)-1, IL-6, and interferons.
These mediators act at the level of the organum
vasculosum of the lamina terminalis in the central
nervous system, inducing synthesis of prostaglandins,
which are the central mediators of fever