Is it unhealthy to sleep from 12 p.m. To 9 p.m. And stay awake at night?

I'm currently visiting my parents and sleep from 12 p.m. To 9 p.m. During the day and stay up all night because I'm a nocturnal person. I'm almost only at home watching movies or playing PlayStation with my brother. Is that unhealthy?

For a long time it could be unhealthy… But as long as you have no complaints everything is okay?!

As long as you feel good, it's healthy. Your body is already telling you whether it is good or not. Everything else is nonsense because so many factors have to be taken into account.

Nobody except you can tell yourself if something is good for you.

Nevertheless, there are disadvantages such as That you can no longer see the sun, which can lead to vitamin D3 deficiency.

But as I said, if you are well, I wouldn't pull myself.

The body knows no time, only a rhythm

As long as you get enough vitamin D, you don't need sun

I would try using a daylight lamp at 9pm to replace the sunlight. Otherwise you will end up feeling like the sailors in the submarines, where you had to adjust the lighting accordingly.

Well try it out for the next 50 years and tell us again how it was.

This rhythm is based on day & night or light & dark.

Usually it does, but it doesn't prevent anyone from doing it at night
to still have full lighting and, if necessary, to lower the blinds during the day.

Lighting by lamps is not the same as sunlight, which is e.g. Needs to produce vitamin D.

Yes i know that.
But to adapt its surroundings to light & dark,
is also feasible with lamps.