Maybe not only a few days, but also several years (if this is, for example, a lethargic dream).
If a person sleeps for several days in a row, then it may be a neurological disease, such as hypersomnia (read more here: https://nevrology-md.ru/news/neurology/hypersomnia- disease- long-sleep ).
In theory, this is possible, but a person will constantly wake up. On day 2-3, the body will become very lethargic, the person will literally fall off his feet. Several similar experiments were carried out, where the subjects, a couple of days after the start of the experiment, needed light medical attention in order to normalize their condition.
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