Regarding Zalmanov's theory - the common reason of depression, weariness and lot of other illnesses is metabolism disorder, especially for people older 40-45.
To remove this illness you have to renew/restore your body metabolism mechanism.
Zalmanov invented special emulsions(1950-1955) and used them to cure people. His method was proven and accepted by French Ministry of Health.
Believe me or not, but I use Zalmanov emulsions myself and they work perfect.