It’s unethical to do X when X is expected to harm the study subjects. Exceptions are sometimes made for interventions with terminally ill patients, but in gener

It’s unethical to do X when X is expected to harm the study subjects. Exceptions are sometimes made for interventions with terminally ill patients, but in general studies that are expected to harm subjects are not approved by ethics boards. They could reasonably do an intervention study that only reduces bedroom light to confirm if that corrects depression on subjects.