In the description of jāgariyānuyoga (“practice of wakefulness”) here, as to pubbarattāpararattaṃ (“before the night and after the night”), the period before the part of the night called midnight is “before the night”; by this both the first watch and the period after the meal are included. The period after that part of the night is “after the night”; by this both the last watch and the period before the meal are included. But the middle watch is not included as being the time for the dispelling of the bhikkhus’ sleep and weariness.
Jāgariyaṃ (“practice of wakefulness”) is practice of wakefulness as being the state of not sleeping. Anuyutto (“devoted to”): he is devoted to, joined to, that cultivation, development called practice.
But in its description by the words idha bhikkhu divasaṃ (“here a bhikkhu by day”) the three parts of the day are included, namely, morning, noon and evening. Cankamena nisajjāya (“while walking and sitting”): one who dwells the whole day in only this pair of postures, purifies the mind from mental obstruction, from states productive of obstruction and from the five hindrances or from all unprofitable states, he cleanses it, liberates it from those states. But here standing is not included; but it should be included too by making it connected with walking and sitting.
Paṭhamayāmaṃ (“in the first watch”): in the whole first watch.
Majjhimayāmaṃ (“in the middle watch”): in the middle watch called a sixth portion of the night and day.
Sīhaseyyaṃ (“in the lion’s sleeping position”): here there are four sleeping positions, the sleeping position of one who enjoys the sense desires, the ghosts’ sleeping position, the lion’s sleeping position and the Tathāgata’s sleeping position.
Herein, the sleeping position of one who enjoys the sense desires is this: ‘Mostly, bhikkhus, beings who enjoy the sense desires sleep on the left side’ (A ii 244); for among these there is mostly no lying down on the right side.
The ghosts’ sleeping position is this: ‘Mostly, bhikkhus, ghosts sleep face upwards’ (A ii 244); for ghosts are beings with little flesh and blood and, consisting of skeleton, are unable to lie down on one side; they sleep face upwards only.
The lion’s sleeping position is this: ‘Mostly, bhikkhus, the lion, king of beasts, puts his tail between his legs and sleeps on his right side … . is glad’ (A ii 245); for owing to prominence of the fire [element] the lion, king of beasts, places his two fore feet in one place and places his hind feet in one place, he puts his tail between his legs, he observes the position of his fore feet, hind feet and tail, he places his head on the top of his two fore feet and sleeps. And on waking up after sleeping in the day he does not wake in fright. But he discerns the position of his fore feet, etc. If anything is out of place he is downcast, thinking: ‘This is not becoming to your birth nor to your bravery,’ and he remains lying there, he does not go out to his resort. But if nothing is out of place he is happy and contented, thinking: ‘This is becoming to your birth and to your bravery,’ and getting up he stretches with the lion’s stretch, shakes his mane and after roaring the lion’s roar three times, he goes to his resort (cf. AA iii 218).
But it is the sleeping position of the fourth jhāna that is called the Tathāgata’s sleeping position. Among these [four sleeping positions] it is the lion’s sleeping position which has been handed down at this point; for this is called the supreme sleeping position because of being the posture which has prominence of the fire element.
Pāde pādaṃ (“with one foot overlapping the other”): the left foot on the right foot. Accādhāya (“overlapping”) = ati + ādhāya, placed one a little beyond the other. For when the ankle presses on the ankle and the knee on the knee, [painful] feeling continually arises, the mind is not one-pointed and the sleeping position is uncomfortable. But since he does not make them press, when they are thus placed a little beyond, [painful] feeling does not arise, the mind is one-pointed and the sleeping position is comfortable. Hence it is said “with one foot overlapping the other”.
Sato sampajāno (“mindful and clearly comprehending”): being possessed of both mindfulness and the understanding of clear comprehension. By this is expounded mindfulness and clear comprehension that lays well hold [of its object].
Uṭṭhānasaññaṃ manasikāritvā (“bringing to mind the perception of [the time for] arising”): having established in his mind perception of arising which has decided the hour of arising thus: ‘I shall arise at such and such an hour,’ since one who has lain down after so doing is bound to arise at the time decided on.
(Dispeller of Delusion II 70-1)