Welcome to HealthcareMagic.From what i could gather, it could be that he works late night or undergoing some kind of stress
and is not having a quality sleep. Let me tell you, even sleep deprivation
may also lead to all what you have mentioned.So firstly please try to talk to him, while keeping your calm, and find out what is bothering him. Give him assurance, being his sister that all is going to be well. If still things persists, he may be taken to a psychiatric physician.There are certain tests done of the blood and or urine, from which the presence or amount of any illicit drugs can be found out. So if prescribed by the psychatrist, you may go ahead with the same. But meanwhile, I would suggest you to give him as much mental/ emotional support as possible.And try to gain his confidence so that he starts confiding to you about his day to day activities, which help you guide him better. Hope I on behalf of HealthcareMagic Team, could guide you in proper way.Wishing your brother a quicker recovery.