Upvote:0
There are several online articles that relate to the question of sleeping upright:
Why do Buddhist monks sleep upright?
Upvote:2
From Vissudhimagga:
The benefits are these. The mental shackle described thus, “He dwells indulging in the pleasure of lying prone, the pleasure of lolling, the pleasure of torpor”, is severed; his state is suitable for devotion to any meditation subject; his deportment inspires confidence; his state favours the application of energy; he develops the right practice.
The adept that can place crosswise
His feet to rest upon his thighs
And sit with back erect shall make
Foul Mára’s evil heart to quake.
No more in supine joys to plump
And wallow in lethargic dump;
Who sits for rest and finds it good
Shines forth in the Ascetics’ Wood.
The happiness and bliss it brings
Has naught to do with worldly things;
So must the sitter’s vow befit
The manners of a man of wit.
Greed subsides.
Thus the Sitter's Practise is the only recommended practise connected to energy.
Upvote:3
The practice of sleeping in a sitting posture can be explained as one of the 13 Dhutanga.
- Sitter's Practice (nesajjik'anga) — living in the three postures of walking, standing and sitting and never lying down.
The advantages of sleeping less as described by the Buddha can be found in Jāgariyasutta
Vigilance
This was said by the Lord…
"Bhikkhus, a bhikkhu should be vigilant; he should live mindful, clearly comprehending, concentrated, happy and calm, and should know when it is suitable to cultivate those things that are wholesome. Bhikkhus, for a bhikkhu who is vigilant and living thus, one of two fruits is to be expected: final knowledge here and now or, there being some residual defilement, the state of non-returning."
You vigilant ones hear this:
Wake up, you who are asleep!
Vigilance is better than sleep:
There is no fear for the vigilant.One who is vigilant and mindful,
Comprehending and concentrated,
Joyful and calm in his thoughts,
By rightly investigating the Dhamma
With unified mind, will in time
Destroy the darkness of ignorance.Therefore be devoted to vigilance,
An ardent, discerning, meditative bhikkhu.
Having severed the fetter of birth and decay,
One may here and now attain
Enlightenment which is supreme.
Note that the pali word 'Jāgaro' which means 'deprive sleep' is translated as 'vigilant' in the above sutta translation.