Prabhupada: How many hours you are sleeping?
Malati: About six to eight.
Prabhupada: That is not much. Sixteen... It takes only two hours, sixteen rounds. Huh? Two hours, or more than that?
Malati: Two hours is all it takes to do the rounds.
Prabhupada: So you have to spend two hours for Krsna out of twenty-four. (walks for awhile and chants japa) Yes?
Devotee (1): Is there something wrong with sleeping eight hours?
Prabhupada: Sleeping and eating, this is the material disease. Sleeping, eating, mating... So they should be reduced as much as possible.
Devotee (1): If you're still tired...
Prabhupada: No, you can sleep till you are refreshed. Somebody's refreshed by sleeping four hours. Somebody is refreshed by sleeping ten hours.
Malati: But we should not sleep when we have, in place of our devotional service.
Prabhupada: No, of course not. Devotional service is first.
Malati: So if we miss some sleep we should do it.
Prabhupada: We should forego sleeping even. The real regulated life is that if sixteen rounds is not completed, then we have to forego sleeping. You should take out hours from sleeping. We should be... The main thing is that we should always be careful that... We are going, we have taken up a very responsible task, Krsna consciousness. So we should be very much careful in discharging the duty. The devotee should be so much careful that he'll always see "Whether this moment is spoiled or utilized?" Avyartha-kalatvam [Cc. Madhya 23.18-19]. Avyartha-kalatvam, that "My time may not be wasted." He should be so careful, "Whether my time is being wasted?" and time wasted, the time we engage for our bodily necessities, that is wasted. Generally, conditioned souls, they are simply wasting their time. Only the period which we have engaged in Krsna consciousness, that is utilized. So we should be very much careful whether time is being wasted or being utilized.
Morning Walk at Stow Lake -- March 23, 1968, San Francisco