Has a teacher referred to sleep as a form of 'lazy nirvana'? The other night at a group meditation meeting, I mentioned to another practitioner that sleep is a 'lazy form of Nirvana'. 

My memory tells me that Tara Brach or another teacher jokingly referred to sleep in that way, but after looking on Google, I can't find the reference :\ 

I would feel a little guilty if my reference was false, but I know that Nirvana is in a lot of ways the opposite of sleep and I'm sure she did too.

I ask this as a joke, but has anyone heard of sleep referred as a 'lazy form of Nirvana?' If so, which teacher made that reference?
Sleep is not really Nibbana because Nibbana is defined as the "uprooting" &amp; "destruction" of the mental defilments, as follows:


  To whatever extent there are phenomena conditioned or unconditioned, dispassion is declared the foremost among them, that is, the crushing
  of pride, the removal of thirst, the uprooting of attachment, the
  termination of the round, the destruction of craving, dispassion,
  cessation, nibbāna.
  
  AN 4.34


In sleep, the mental defilements of an non-fully-enlightened mind remain dormant as "underlying tendencies". Therefore, sleep cannot be Nibbana. 

However, the teacher Bhikkhu Buddhadasa make some comments about how the 'Nibbana element' operates in everyday life, here: Nibbana for Everyone. which includes 'sleep'. 


  Nibbāna is one of the dhātus (natural elements). It is the coolness that remains when the defilements – greed, anger, fear, delusion –
  have ended.
  
  Any reactive emotion that arises ceases when its causes and conditions cease. Although it may be a temporary quenching,
  merely a temporary coolness, it is still Nibbāna, even if only
  temporarily. Thus, there’s a temporary Nibbāna for those who can’t yet
  avoid some defilements. It is this temporary Nibbāna that sustains the
  lives of beings who continue hanging onto defilement. Anyone can see
  that if the egoistic emotions existed night and day without any pause
  or rest, no life could endure it. If such life didn’t die, it would go
  crazy and then die in the end. You ought to consider carefully the
  fact that life can survive only because there are periods when the
  defilements don’t roast it. These periods outnumber the times when the
  defilements blaze.
  
  These periodic Nibbānas sustain life for all of us, without excepting even animals, which have their levels of Nibbāna, too. We are able to
  survive because this kind of Nibbāna nurtures us, until it becomes the
  most ordinary habit of life and of mind. Whenever there is freedom
  from defilement, then there is the value and meaning of Nibbāna. This
  must occur fairly often for living things to survive. That we have
  some time to relax both bodily and mentally provides us with the
  freshness and vitality needed to live.