Visuddhimagga XIV-167

Tattha thinanatā thinaṃ. Middhanatā middhaṃ. Anussāhasaṃhananatā asattivighāto cāti attho. Thinañca middhañca thinamiddhaṃ. Tattha thinaṃ anussāhalakkhaṇaṃ, vīriyavinodanarasaṃ, saṃsīdanapaccupaṭṭhānaṃ. Middhaṃ akammaññatālakkhaṇaṃ, onahanarasaṃ, līnatāpaccupaṭṭhānaṃ, pacalāyikāniddāpaccupaṭṭhānaṃ vā. Ubhayampi arativijambhikādīsu ayonisomanasikārapadaṭṭhānaṃ.

此中：心的沉重为「惛沉」。心的倦睡为「睡眠」。即说此等是精神萎靡缺乏勇气不堪努力之意。惛沉与睡眠合为「惛沉睡眠」。此中：惛沉以不堪努力为特相；有除去精进的作用；以心的消沉为现状。睡眠以不适业为特相；有闭塞（其心）的作用；以心的沉滞或眼的昏昏欲睡为现状。这两种都是由不乐及欠伸等而起不如理的作意为近因。

Ñ(XIV,167): Herein, (xliii) stiffening (thinanatā) is stiffness (thina); making torpid (middhanatā) is torpor (middha). The meaning is, paralysis due to lack of urgency, and loss of vigour. The compound thinamiddha (stiffness-and-torpor) should be resolved into thinañ ca middhañ ca. Herein, stiffness has the characteristic of lack of driving power. Its function is to remove energy. It is manifested as subsiding. Torpor has the characteristic of unwieldiness. Its function is to smother. It is manifested as laziness, or it is manifested as nodding and sleep. The proximate cause of both is unwise attention to boredom, sloth, and so on.