Sattva and Svapna
According to the Vedic tradition of yoga and Ayurveda, one should come in a state of sattva before going to sleep for getting a deep, healthy and rejuvenating sleep. This sleep is devoid of claptrap dreams about the activities of the day. A regular practice of bringing the mind to sattva state before sleep transforms the nature of sleep as well as what we dream during sleep.
According to Patanjali, during sleep our senses are partially closed to the new knowledge. Patanjali uses the word partial, because if someone makes noise or flashes light on us, we get the sensuous experience of these actions even during sleep. Besides that, Patanjali argues that we are always aware about the nature of our sleep. Upon getting up, we know if we slept good or bad or deep, etc.
Though closed to the new knowledge during sleep, the old knowledge which we have due to retention and memory still circulates in out head and appears in the form of dreams.
Let us look at some medical aspects of our dreams and learn how we can transform the nature of our sleep and dreams.