Roga(disease) is the abnormalcy of the doshas; whereas their normalcy is health. Disease are of two kinds- Nija (organic, endogenous, internal) and Agantu (external, exogenous); likewise even their Adhisthana (abode, dwelling, seat) is also two – Kaya (body) and Manas (mind).
Manodoshas (Doshas of the mind):
Rajas and Tamas are considered as the two doshas of the mind.
According to the Upanishads everything in the universe is said to consist of the three Mahagunas- the Satva, Rajas, Tamas.
Sattva, equilibrium is a normal state of mind in which a person can discriminate accurately. It represents intelligence, joy, enthusiasm & purity.
Rajas, or motion in which excessive mental activity weakens discrimination. It represents emotions, force, quickness and instability.
Tamas, or inertia, a state in which insufficient mental agility weakens discrimination. It represents inactivity, ignorance, laziness and stability.
Rajas when predominant gives rise to over-activity, haste, emotions like anger, bravery, passion and attachment; persons of Rajo guna will be very emotional, highly irritable & get into fits of anger and violence most of the time.
Tamas when predominant gives rise to ignorance, grief, lack of enthusiasm & timidity. Persons of Tamo guna will be slow in all activities, foolish, worried & sleepy.
Sattva guna is most conducive to health.