Each guna is associated with certain characteristics. Rajas is associated with energy; sattva promotes intelligence; and tamas is associated with the color black, night time, negative/dark energy and inactivity.
Those with tamas domination are lazy, dull, ignorant, inactive and greedy. They have psychological blockages. Owing to lack of self-care, their energies remain stagnant, causing poor health conditions. They are also easily and negatively influenced.