De somno et vigilia theses ad disputandum propositae

XIIII.
...or some being deficient, we judge that all sleep is to be ascribed immediately.

XIII.

Yet in sleep, the cavities and pathways are very often not closed, especially when sleep happens due to evacuation, labor, and excessive waking; and if they ever do induce sleep, they do not do so without the intervention of something else.

XIIII.

The common faculty of sensing itself, whether occupied, corrupted, or weakened, does not always do the same thing. Because sleep creeps in while the animal is entirely strong, and especially when nothing else is being done.

XV.

The innate heat, which flows from the heart, since by the consensus of philosophers and doctors it contributes to the determined actions of parts only in a general way (that is, by providing act to the spirit and the innate heat, in individual parts disposed naturally or otherwise), cannot be the proper and per se cause of sleep.

XVI.

Nor is there reason to think that the brain is deprived of its presence and motion at the time of sleep. Since even sleeping, one lives, imagines, moves; they have stronger pulses; they digest food more successfully in the brain; they mitigate and digest excrements; they restore animal spirits, which cannot be done without a significant quantity and motion of heat; not to mention the redness of the face, sweat of the head in those sleeping, the revocation of heat in syncope fainting, swoons, fever accessions, and great cold without sleep: all of which quite clearly testify that a defect of heat is not the proximate cause of sleep.