Yoga sutra 1.38
svapna-nidrā jñāna-ālambanam vā
Also meditate on that which comes during your sleep
Knowledge can be gained from deep sleep and from a dreaming state. It is a mechanism for supporting the mind and attaining peace. Sometimes you dream the most blissful things. Try to think of that dream as real and meditate on it.
Damian Cadman-Jones is an authorised teacher of Prana Vashya Yoga™