According to the Upanishads, everything in the universe is said to consist of the three Mahagunas-
Sattva or the equilibrium is a state of mind in which a person can discriminate accurately. It represents intelligence, joy, enthusiasm & purity. Sattva guna is most conducive to health.
Rajas or motion is a state of mind in which excessive mental activity weakens discrimination. It represents emotions, force, quickness and instability.
The predominance of Rajas gives rise to over-activity, haste, emotions like anger, bravery, passion and attachment; A person of Rajo guna tends to be very emotional, highly irritable & be susceptible to fits of anger and violence often.
Tamas or inertia is a state of mind in which insufficient mental agility weakens discrimination. It represents inactivity, ignorance, laziness and stability.
The predominance of Tamas gives rise to ignorance, grief, lack of enthusiasm & timidity. A person of Tamo guna tends to be slow in all activities, worried & sleepy.