In the philosophy of Yoga, all matter in the universe arises from the fundamental substrate called Prakriti. From this ethereal Prakriti the three primary gunas (qualities) emerge creating the essential aspects of all nature—energy, matter and consciousness. These three gunas are tamas (darkness), rajas (activity), and sattva (beingness).
 

Tamas is a state of darkness, inertia, inactivity and materiality. Tamas manifests from ignorance and deludes all beings from their spiritual truths.  To reduce tamas avoid tamasic foods, over sleeping, over eating, inactivity, passivity and fearful situations.  Tamasic foods include heavy meats, and foods that are spoiled, chemically treated, processed or refined.
 

Tamas - accounts for restraint and inertia.  Experienced psychologically as delusion, depression and dullness.  Classical Yoga: - when tamas (obscurity, heaviness) predominates, consciousness is sthiti - inert, punged into a state of repose and torpor

 

Tamasic Food is meat, alcohol, tobacco, garlic, onions, other fermented foods (pickles and vinegar for example), and either over-ripe or stale foods. These foodstuffs are seen not to benefit either the body or mind and energy, Prana, is reduced producing inertia and dark moods. The body’s resistance to disease is weakened and consequently the whole being becomes inert, greedy and prevents one from seeing the spiritual truths.

The mind’s psychological qualities are highly unstable and can quickly fluxuate between the different gunas.  The predominate guna of the mind acts as a lens that effects our perceptions and perspective of the world around us. Thus, if the mind is in rajas it will experience world events as chaotic, confusing and demanding and it will react to these events in a rajasic way.

All gunas create attachment and thus bind one’s self to the ego.  “When one rises above the three gunas that originate in the body; one is freed from birth, old age, disease, and death; and attains enlightenment” (Bhagavad Gita 14.20).  While the yogi/nis goal is to cultivate sattva, his/her ultimate goal is to transcend their misidentification of the self with the gunas and to be unattached to both the good and the bad, the positive and negative qualities of all life.