Sleep - What about it? What are the proper relax / Sleep practices for a practitioner of meditation methods?

As to Buddhist point of view what is sleep and how to cope with it?
What are the proper relax / Sleep practices for a practitioner of meditation methods?


If you do Metta meditation before sleeping you are better off, as one benefit of Metta is you sleep well. ((Aṭṭha) Mettânisansa Sutta, (Ekā,dasa) Mettânisansa Sutta)


  As to Buddhist point of view what is sleep and how to cope with it?


This is when your Bhavanga is active and the revolutions of the Dependent Origination cycles has momentarily stopped. (The Doctrine of Paticcasamuppada - The Law Of Independent Origination - By U Than Daing, page 32). An essay "The Unconscious" by Piya Tan discusses action action that done when sleeping.

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Thoughts of others on the subject of sleep:

On deep sleep and bhavanga:


  The idea of an underlying skilful base to the mind is developed further in the
  Abhidhamma, which analyses the constituents of consciousness in detail. For a
  human rebirth to have occurred, the bhavakga, or consciousness to which the
  mind returns at rest, is skilful, whether with the two roots of non-greed and nonhatred,
  or more usually, with three roots, of wisdom, non-greed and non-hatred.
  This consciousness will be present whenever the mind enters bhavakga, either
  momentarily at the end of each thought-process, or during deep sleep. For all born
  as humans, the state of bhavakga is a reflection of the skilful state of mind that
  must have been present at the moment of death as a governing factor for the
  relinking consciousness. It is passive, however, and this predisposition needs
  active cultivation during waking life. Only when skilful consciousness is present
  during daily life, or during meditation, does the mind become actively bright and
  radiant. According to the theory this happens, for instance, at the moment of
  giving, of being alert and interested or when practising jhana: the active part of
  the thought-process ( javana) is then free from defilements. Those practising
  meditation are ‘bringing into being’ a consciousness which is thought to be a kind
  of birthright, but which needs cultivation. In Buddhist countries the human realm
  is considered particularly important for spiritual work. Birth in heaven realms is
  pleasant but lacks the suffering to encourage spiritual work; the realms of
  animals, ghosts and hell beings are considered far too painful for the path, and it
  is difficult, though not impossible, for such beings to find a skilful rebirth. It is
  said that the Buddha always has a human birth as his last existence after many
  lifetimes spent preparing to teach others. One sutta compares rebirth in a hell
  realm as entering into a pit of coals, that of a heaven realm to a stay in a luxurious
  mansion. The human realm, however, is like a man sitting in the shade of a
  tree in a hot climate, also the classic conditions for the practice of meditation
  (see M I 76–7).


Source: Buddhist Meditation: An anthology from the Pali canon, by Sarah Shaw

On reduced need of sleep for meditations


  Similarly, when you go to bed at night, close your eyes and feel sensation anywhere within the body. If you fall asleep with this awareness, naturally as soon as you wake up in the morning, you will be aware of sensation. Perhaps you may not sleep soundly, or you may even remain fully awake throughout the night. This is wonderful, provided you stay lying in bed and maintain awareness and equanimity. The body will receive the rest it needs, and there is no greater rest for the mind than to remain aware and equanimous. However, if you start worrying that you are developing insomnia, then you will generate tensions, and will feel exhausted the next day. Nor should you forcefully try to stay awake, remaining in a seated posture all night; that would be going to an extreme. If sleep comes, very good; sleep. If sleep does not come, allow the body to rest by remaining in a recumbent position, and allow the mind to rest by remaining aware and equanimous.


...


  Firstly, you will need less time for sleep.


The Discourse Summaries

Mental impurities inducing sleepiness:


  Another enemy is laziness, drowsiness. All night you slept soundly, and yet when you sit to meditate, you feel very sleepy. This sleepiness is caused by your mental impurities, which would be driven out by the practice of Vipassana, and which therefore try to stop you from meditating. You must fight to prevent this enemy from overpowering you. Breathe slightly hard, or else get up, sprinkle cold water on your eyes, or walk a little, and then sit again.


The Discourse Summaries

On involuntary action during sleep:


  Unconscious actions are, however, still regarded as morally motivated, but should be
  understood to differ from involuntary actions or reactions. Sue Hamilton, for example, discusses the
  possibility of involuntary reactions and how it is accounted for:
  
  
    I have suggested that if one is not conscious of a sound then one has not heard it. We
    can, however, sometimes react ―involuntarily‖ to a sound without being conscious of it: in sleep,
    for example, a loud sound can cause one to make a movement even if there is absolutely no consciousness
    of the sound at all. We also experience peripheral awareness which we do not seem to
    be conscious of. We regularly avoid obstacles in our path while our attention is wholly elsewhere,
    for example. Though such experiences of peripheral awareness might indicate the minimal level
    to which consciousness of, or awareness, operates, this question is not explicitly dealt with in the
    Sutta Piaka. Nor is the experience of involuntary reactions explained. This is a significant omission
    because involuntary reactions such as wet dreams became the subject of controversy in the
    early Buddhist sangha: if they are unconscious, do they constitute a volition with moral implications?
  


Source: The Unconscious

Though not in a Buddhist perspective this course also might be of some interest: Sleep: Neurobiology, Medicine, and Society