Bhagavad Gita Verse 14.8

हे अर्जुन सब देहाभिमानियों को मोहित करने वाले तमोगुण को तो अज्ञान से उत्पन्न जान । वह इस जीवात्मा को प्रमाद, आलस्य और निद्रा के द्वारा बांधता है|

But you should also know O Arjuna, that darkness and evil born out of the TAMAS GUNA, exists mainly because of the ignorance of man in this world. TAMAS creates laziness and dullness. One loses the value of time and no longer desires to work or to take part in constuctive action.