Recently going through this question (that has been put hold as off-topic; and commented for more appropriate to CogSci.SE) ; to me it looked highly like a biology (physiology) question such as this sleep-wake cycle question.
So it seems the border between Biology, Cognitive-science and Health(or medical-science); is very much blurry, interrelated as well as quite subjective.
So; do-we have some principle to technically/ officially consider a question as biology or cog-sci or health?