Aloka-sanna

Āloka-saññā: Perception of light. The recurring canonical passage reads: Here the Bhikkhu contemplates the perception of light. He fixes his-mind to the experience of the daylight; as at day-time so at night, and as at night, so in the day. In this way, with a clear and unclouded mind, he develops the stage of mind that is full of brightness. It is one of the methods of overcoming drowsiness, recommended by the Buddha to Mahā-Moggallāna A. VII, 58. According to D. 33, it is conducive to the development of 'knowledge and vision.' 
==References==
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952. 
Category:Pali terms