East-facing rooms and morning light: what science says

Vastu texts favour larger openings and lighter construction in the north and east, and heavier walls in the south and west. The east is linked with Sūrya and the start of the day.

Office workers with windows received more daylight and slept on average about 46 minutes longer per night than those without (Boubekri et al., 2014).

Higher circadian-effective light in the morning was linked to falling asleep faster and better mood (Figueiro et al., 2017). East openings are the easiest way to get that morning light indoors.

In the Indian sub-continent the low western sun of the afternoon adds the most heat to walls and glass. Thick west and south walls with fewer openings reduce that gain — a building-climate principle described by Givoni.

None of this shows that direction itself brings luck or illness. The benefit comes from light and heat, so a well-designed window in any direction can deliver part of it.