成唯識論述記 7.109

7.109

述曰：睡眠與欲界意識俱一切受相應，以睡行相通歡，故喜受俱；通戚，故憂受並；中庸，故捨受俱，如次第配。

The Commentary states: Torpor is associated with all feelings that accompany the manovijñāna of the desire realm: because the ākāra of sleep extends to joyfulness, it is accompanied by the feeling of joy; because it extends to distress, it is joined with the feeling of sorrow; because it extends to neutrality, it is accompanied by the feeling of equanimity—matched in this respective order.