Researchers in Japan recently conducted a study of nursing - home residents who suffered from insomnia, and they found that the poor quality of the subjects ’ sleep was related to their limited daily exposure to environmental light.
يمكن ان تكون المشكلة نقصا في التعرُّض للضوء الساطع خلال النهار ،‏ وخصوصا اذا كنتم مسنين .‏