Much research has been done to monitor the various stages of sleep and to try to determine what is taking place during each stage. People have been experimenting with learning during sleep, and some people actively ‘program’ their minds before they go to sleep to solve certain problems they are facing, letting the subconscious work out the solutions. Aspirants frequently report dreams or experiences that occur during sleep that help to guide them or solve issues they are facing. Many find that teachers or gurus come to them and provide instruction or guidance. While for the most part sleep is an unconscious period for the waking mind, these breakthrough experiences make it clear that a lot is going on during sleep-time.
Sleep, however, is frequently a time when the waking consciousness not only departs temporarily, but it can be a time when the overall state of consciousness falls under the influence of tamas, and progress made during the day is lost during the night. This gives the seeker the feeling of having to always repeat and rebuild the experience each day upon waking. Several strategies have been developed including rising for meditation at 3 am, the ‘Brahma muhurta’ or attempting to overcome the power of sleep itself through various disciplines and austerities. Neither of these methods fully resolve the issue however.
Nowadays, a practice known as Yoga Nidra has gained substantial recognition as a mechanism for bringing deep rest to the body while holding a state of consciousness that is effortless and at the same time luminous. This is based on ancient teachings of the sages relating to the various stages of the development of consciousness and the various states of sleep. It has become clear that the physical mind can be programmed through an act of focus, will and aspiration prior to sleep, so that it does not lose the thread of awareness entirely and sleep can be an active continuation of the daily yogic practice.
Sri Aurobindo notes: “You have to start by concentrating before you sleep always with a specific will or aspiration. The will or aspiration may take time to reach the subconscient, but if it is sincere, strong and steady, it does reach after a time — so that an automatic consciousness and will are established in the sleep itself which will do what is necessary.”
“At night, you have to pass into sleep in the concentration — you must be able to concentrate with the eyes closed, lying down and the concentration must deepen into sleep — that is to say, sleep must become a concentrated going inside away from the outer waking state. If you find it necessary to sit for a time you may do so, but afterwards lie down keeping the concentration till this happens.”
Sri Aurobindo, Integral Yoga: Sri Aurobindo’s Teaching and Method of Practice, Chapter 10, Difficulties in Transforming the Nature, Sleep, pp 311-314