Most definitely normal. They shroud themselves in the night it's called Foliar nyctinasty it'sbelieved to conserve energy and help keep core temps warmer during nightfall.
Yes, at night, the leaves of the plants tend to fall; they sleep, and during the day, the leaves of the plants seek the light and rise towards it! Everything is good, happy growing!
Yeah, mine did the same last year every night. I thought they were in too small pots, so I repotted them and that helped, but as soon as the sun comes out, they start stretching again. So I don't know if it's the plant's roots that are freezing and waiting for sun and warmth.