Yoga Nidra is a practice which is normally the last component of a Yoga class, where the student is in Shavasana ( Corpse pose). Having performed the asanas and Pranayama the practitioner is gradually brought into Shavasana and might require a blanket as the body can get cool during this practice. During this practice the student is gradually and progressively led through different stages until a state of deep conscious relaxed awareness may be experienced.It is indeed a gem of a practice and is considered a 'Pratyahara' practice as per Raj Yoga ( withdrawing the mind from the senses). Using verbal instructions, the student is led gradually from the outer most, Annaymaya Kosha ( sheath or layer) through the Pranamaya Kosha ( Prana is the life force within us), Manomaya Kosha ( mental/emotional layer) to the Vignanamaya Kosha (wisdom or intuitive layer). To be experienced, this state is very relaxing and blissful .