Sleeping is very dangerous. It is to be understood that I am under the clutches of maya, the more we sleep, because the symptom of tamo-guna is laziness and sleep. This is the symptom of tamo-guna, laziness and sleeping.

(Srila Prabhupada, lecture on Srimad-Bhagavatam 1.2.20 – Vrndavana, October 31, 1972)