Inhabitants of the fifth of the nine abodes of beings (sattāvāsā). These beings are unconscious and experience nothing (A.iv.401). As soon as an idea occurs to them they fall from their state (D.i.28). Brahmin ascetics, having practised continual meditation and attained to the fourth jhāna, seeing the disadvantages attached to thinking, try to do away with it altogether. Dying in this condition, they are reborn among the Asaññasattā, having form only, but neither sensations, ideas, predispositions nor consciousness. They last only as long as their power of jhāna; then an idea occurs to them and they die straightaway (DA.i.118).
The Andhakas held that these devas were really only sometimes conscious, which belief the Theravādins rejected as being absurd (Kvu.262).
The Elder Sobhita was once born among the Asaññasattā and could remember that existence. These devas are long-lived. ThagA.i.291.