Sounds reasonable given it was more involved than typical/simple (simple?) ACDF. The body often requires more rest/sleep during healing.

Not a story I like relating, but my grandmother once had a cat that went through a ringer washer (don't ask—it wasn't abuse/intentional). The cat somehow got itself on top of her refrigerator (one that got warm on top) and slept there for something like 3 weeks. After that, it was fine and led a long healthy (AFAIK) life.

Yeah, it's one of those family stories that begs credulity, but the point is that healing occurs during sleep because the energy isn't being expended on other bioligical activities, blood chemistry (e.g. hormone production) is different, etc.

Does Sleeping Help You Heal?

Doc