hello user , i understand your concerns . such symptoms of early fatigability - difficulty concentrating on work and trouble having good sleep can be part of a dysthymic/depressive illness - especially if some other symptoms like feeling low mood , irritability , pessimism for future , low self esteem , appetite irregularities are there - The external cause is however need to be much apparent though - you should consult any good psychiatrist for evaluation and treatment with medicines and behavioural therapy , and hopefully you will get your energy and sleep back again . hope i answered your query - if satisfied please rate the answer