Well explained but I really do not know if the circadian rhythm is solely responsible for those jetlag symptoms you highlighted. If such is the case, people whose jobs require night-shifts should be experiencing the same symptoms. Have you heard about motion sickness? I think that could also be in play as far as the symptoms you mentioned are concerned.
If the circadian rhythm is actually true to details, why then do people sleep during the day?
I think that the circadian rhythm is at play, but as I said in the other comment, it's not solely responsible.
Plus individual people have a stronger or weaker circadian rhythm.
Yeah the night-shift sleep disorder is also a type of jet lag and yes people who work shifts experience jet lag. I have heard of motion sickness and some of the symptoms I highlighted are seen there too. I’ve also done well to highlight that those symptoms may be indicative of jet lag but it doesn’t go as much to confirm jet lag.
The circadian rhythm doesn’t solely regulate sleep. Sleep Homeostasis also comes into play when we’ve not had enough sleep and compensates for lost sleep basically by making us sleep during the day. So yes this is why we sleep during the day.