I understand your concern towards your friend. From whatever you have mentioned looks like he might be suffering from few depressive symptoms, may be due to personality issues. However information regarding his sleep, hunger and energy levels also would be more helpful to decide on the severity of his problem. If suicidal he should seek immediate professional assistance. It is manageable with appropriate treatment. Some therapy sessions along with medical help might be useful for him. I would also be more than happy to help you with that if you are looking for further online assistance. Discussions will be held confidential. You can directly consult with me through Practo as needed. Online chat consultation is also available.