Chronobiology enables the study of the body’s behavior. Up until 2002, we were only able to distinguish two types of photoreceptors in the eye - cones (responsible for vision at night) and rods (responsible for vision during the day). In 2002, researchers made a discovery which enabled the increase of the field of practice of light therapy : in fact, a third type of photoreceptor exists, this time non-visual. Also known as ganglion pigment cells, these photoreceptors are involved in the regulation of circadian rhythms through the effect of light.

The mechanism of light’s effect is made up of different stages:

1. Light penetrates the eye and activates the ganglion pigment cells.

2. The photoreceptors then transform the visual signal into an electrical signal and send it via the optic nerve to our biological clock regulator (the superchiasmatic nucleus).

3. This interprets the signal and via the pineal gland it adjusts the secretion level of the sleep hormone (melatonin) and awake hormones (cortisol, serotonin, adrenaline).

Discover what role light plays on the body

with Roland Pec - sleep specialist and chrono-therapist