Astudent form the following hypothesis if people wear bright clothes they will be happier =what are the problems of this hypothesis.

The situation that the person is in, if the person has a previous issue with depression, if that person is always happy if they are always sad, if they are colorblind so colors don't activate emotions through the retena

I am very fond of colours and especially their psychology, this is something I know a lot about and not all bright colours make you happy for example, red.
Another thing is the meaning of 'bright', different people have different understandings of the word because it can't easily be said what it means exactly. Also, if someone is colour blind or just blind, colour won't affect them in the same way.

Hope this helps :)