Sleep is a most common phenomenon of life; and, though every human being goes through the experience from birth to death, few have any correct knowledge as to the cause of sleep, the nature and purpose of sleep, and how the consciousness functions during those hours of sleep. Some consider sleep to be a waste of time, others indulge in it even beyond the proverbial eight hours. Why is it that some get the needed refreshment in fewer hours than others get in a much longer period? Why do children need more sleep? Why is sleep considered to be a prime necessity during an illness? Theosophy gives definite and precise knowledge on the subject of sleep, and students would be really benefited by a thorough study of the Appendix on Dreams in Transactions of the Blavatsky Lodge, where Madame Blavatsky herself answers a number of important questions put to her. Various aspects of this practical subject are also taken up in U.L.T. Pamphlet No. 11.
Madame Blavatsky in her first monumental work, Isis Unveiled, makes an important statement which at once points out the purpose of sleep: "Night rests humanity from the day's activity, and restores the equilibrium of human as well as of cosmic nature." (I, XXVI)
So the function of sleep is to restore the broken equilibrium, not only in the human kingdom but in the whole of cosmic nature as well. Night is the time for rest after the day's activity. All beings and creatures in Nature's lower kingdoms rest during this period. Only human beings go against the law and turn night into day and spend their time in theatres, cinemas and night clubs till the late hours, missing the advantage that the nightly rest affords. The alternation of day and night, waking and sleeping, activity and rest, is a common fact, and each human being has to make practical application of the great Law of Cycles or Periodicity in his daily life if he would live in harmony with Nature. It operates in the whole of cosmos, and so there is an active period of manifestation followed by the sleep of Pralaya or non-manifestation.
Krishna speaks of it in the Eighth Discourse of the Bhagavad-Gita: "Those who are acquainted with day and night know that the day of Brahma is a thousand revolutions of the yugas, and that his night extendeth for a thousand more." The very first verse of the Stanzas of Dzyan states: "The Eternal Parent wrapped in her ever invisible robes had slumbered once again for seven eternities."
So, from the highest spiritual to the gross material and physical plane, waking and sleeping is the rule of life.
In the Sixth Discourse of the Bhagavad-Gita, Krishna instructs Arjuna in the Divine Discipline:
This divine discipline, Arjuna, is not to be attained by the man who eateth more than enough or too little, nor by him who hath a habit of sleeping much, nor by him who is given to overwatching. The meditation which destroyeth pain is produced in him who is moderate in eating and in recreation, of moderate exertion in his actions, and regulated in sleeping and waking.
So it is essential to be regular in the observance of the hours of sleep and to be moderate—not too much or too little. Rest after a day's work is a necessity. It alone can restore the broken equilibrium. How is it broken? From the moment of waking, every individual receives within himself different types of lives which are but different aspects of the One Life—airy, watery, earthy and fiery lives; mineral, vegetable and animal lives. There is a constant interchange of lives between human beings. Each influences and affects the others and is influenced and affected by those others. Each receives impressions from outside via the senses, and past recollections and future anticipations make him see pictures within himself. So, towards the close of the day he becomes more full of life than on waking and Nature compels him to have a change of polarity. His senses can no longer function, so he is unable to have any objective contacts or objective impressions and is turned within himself, thinking the same thoughts, generating the same kind of desires and feelings on higher or lower plane as during his waking life. But the body and the senses are absolutely quiet, therefore restful. Each human being is born with a certain quality of prana or vitality, weak or strong, pure or impure, and a certain rate of vibration. So each one is able to do only a certain amount of work, receive a certain number of impressions and no more, and the overbalance that takes place must be restored.
Two statements from Transactions will clear the point:
As a man exhausted by one state of the life fluid seeks another; as, for example, when exhausted by the hot air he refreshes himself with cool water; so sleep is the shady nook in the sunlit valley of life. (p. 71)
When questioned as to the process of sleep, H.P.B. answered:
It is said by Occultism to be the periodical and regulated exhaustion of the nervous centres, and especially of the sensory ganglia of the brain, which refuse to act any longer on this plane, and, if they would not become unfit for work, are compelled to recuperate their strength on another plane or Upadhi. (pp. 70-71)
It is this alternate condition of the sunshine of wakeful life and the cool shade of sleep that enables each one to go through his embodied existence for a shorter or longer span of life, determined by the quality of prana or vitality that is his under Karma. That vitality can be changed for better or worse, in terms of his own ideation, habits and mode of existence, and to the extent to which his personal life is harmonized with the spiritual principles. As the One Life is made up of infinitesimal lives, each one can attract to himself those lives that are consubstantial with his own nature. Herein lies the mystery of sleep.
While the body sleeps and rests and recuperates, the thinker within the body carries on his own activity on his own plane. H.P.B. makes an important statement:
Occultism teaches that physical man is one, but the thinking man septenary, thinking, acting, feeling, and living on seven different states of being or planes of consciousness, and that for all these states and planes the permanent Ego (not the false personality) has a distinct set of senses. (Transactions p. 73)
So there are different states through which each thinker passes during sleep, but mainly there are two—the dream or swapna state and the deep-sleep or sushupti state. The thinker works through the inner senses, just as during waking life he uses the physical senses. As each one's mind is occupied during the day, so will it be at night. Therefore it is essential to be vigilant during waking life so that the sleeping hours may be more fruitful, yielding more beneficial results. If the personal consciousness is predominant along one or another line during the day, so will it be at night. If the mind remains on higher level during the day, so wil it be at night. Everyone experiences both these states, but for longer of shorter periods according to one's nature. It is really the deep-sleep state that produces refreshment and recuperation when, minus his fleshly appetites and worldly desires and passions, the unworldly soul partakes of the "banquet of the gods" because he has become like unto a god. It is in this state that poets and writers, artists and musicians, are inspired. It is in this state that prophetic or warning dreams are had. It is in this state that difficult problems are solved. It is a state free from the fetters of earthly existence.
So there are three main states of consciousness, all interdependent. Between waking and deep sleep is the borderland of swapna, which is to be crossed both ways, from waking to deep sleep and from deep sleep to waking; and the less one gets involved in that dream state the better for him. Theosophy recommends purification of heart and mind and brain so that one may not loiter and linger in the dream state but may quickly cross over and plunge into deep sleep. It is also necessary, before putting the body to sleep, to ideate on an inspiring subject so that the thread of ideation may be continued in sleep. Each one is a musician and strikes his notes softly or harshly, harmoniously or discordantly. He has to have his instrument in perfect tune. So also the Divine Ego needs a perfect instrument to sing the song of Life, which is for most individuals not a song but a cry. Theosophy teaches and encourages man to live in harmony with the whole of Nature, to try to make of his body a living temple, so that the Living God may, waking or sleeping, sing the Divine Melody to inspire and uplift all fellow beings.