Nessajika: Sleeping upright not lying down

[gavesako]

This ascetic practice (nesajjika, "sitter's practice") which is undertaken by some monks, apart from causing back and neck problems over long periods of time, also seems to have other side effects. Interestingly, the Buddha never mentions these extreme practices as part of any standard list in the Suttas, and yet they seem to have been practised by some monks and later became standardised in the 13 dhutangas.

See http://www.buddhistchannel.tv/index.php ... 03,0,0,1,0