GABA:
Neurotransmitter in the central nervous system whic has an influence on anxiety and relaxation.

Stressful agent:
"Stressful agent" all factors, internal or external, likely to generate a state of stress on an individual.

Homeostasis:
Tendency of an organism to retain or to regain its equilibrium, threatened by the action of physical or chemical factors, thanks to the mechanism of regulating systems.

Neurotropic:
Recognises substances introducing a specific affinity on the nervous system.

Falling asleep phase:
Sleep is divided into several successive cycles of about 90 minutes. Every cycle consists of 3 distinct phases:
     - a falling asleep phase also called " calm awakening ", during which the cerebral waves decelerate to allow us to fall asleep;
     - a stage of slow sleep, representing more than 2/3 of a cycle of sleep
     - and a stage of paradoxical sleep.
A psychological stress can cause sleeping difficulties. It is generally one of the first reasons of insomnia registered by the individuals suffering from sleep disturbances.

Phytotherapy:
Use of plants or substances of plant origin for therapeutic aims.

Placebo:
In a clinical study, the placebo is the equivalent of a decoy. It must be in every way identical to the studied substance dose (example: in form of capsules of the same form, even colour, the same smell) but containing no active molecule.

Totum:
All the constituents of a plant which provides functional properties.