For the source text click/tap here: Shavuot 25
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We have already noted the basic difference between a neder and a shevua that is commented on by the Gemara. While a neder acts on an object (e.g. a person declares that meat is forbidden to him), a shevua acts on the person (e.g. he accepts upon himself a prohibition that will keep him from eating meat).
The case of the Mishna on our daf, where someone takes a shevua that he will not sleep, will only work if it is an oath, since “sleep” is not an object, and it can only become forbidden by means of a shevua (which will create a prohibition on the person keeping him from sleeping).
We explore the physiology of sleep and insomnia as a mark of asceticism.