Whether nocturnal pollution is a mortal sin?

Objections

Objection 1 : It would seem that nocturnal pollution is a sin. For the same things are the matter of merit and demerit. Now a man may merit while he sleeps, as was the case with Solomon, who while asleep obtained the gift of wisdom from the Lord (3 Kgs. 3:2, Par. 1). Therefore a man may demerit while asleep; and thus nocturnal pollution would seem to be a sin.
Objection 2 : Further, whoever has the use of reason can sin. Now a man has the use of reason while asleep, since in our sleep we frequently discuss matters, choose this rather than that, consenting to one thing, or dissenting to another. Therefore one may sin while asleep, so that nocturnal pollution is not prevented by sleep from being a sin, seeing that it is a sin according to its genus.
Objection 3 : Further, it is useless to reprove and instruct one who cannot act according to or against reason. Now man, while asleep, is instructed and reproved by God, according to Job 33:15,16, "By a dream in a vision by night, when deep sleep is wont to lay hold of men [*Vulg.: 'When deep sleep falleth upon men.' St. Thomas is apparently quoting from memory, as the passage is given correctly above, Question [95], Article [6], Objection [1]] . . . Then He openeth the ears of men, and teaching instructeth them in what they are to learn." Therefore a man, while asleep, can act according to or against his reason, and this is to do good or sinful actions, and thus it seems that nocturnal pollution is a sin.