The Anandamaya kosha or “sheath made of bliss” (ananda) is in Vedantic philosophy the most subtle or spiritual of the five levels of embodied self. It has been interpreted differently according to specific schools of Indian (and also Theosophical) thought.
The Anandamaya kosha in traditional Advaita Vedanta
In Advaita Vedanta the Anandamaya kosha is the innermost of the five koshas or “sheaths” that veil the Atman or Supreme Self. Unlike the next three more outer koshas, it constitutes the karana sarira or causal body. It is associated with the state of dreamless sleep and samadhi.