Hello,
Yes, it is quiet possible to suffer from a depressive episode or any other mental health ailment without any discernable external/environmental reason. Depression is considered in today's contemporary scientific though to be a bio-psycho-social illness. Which means that both in genesis and management approaches biological factors like brain chemicals, receptors, other bodily hormones like
thyroid, other illness like
diabetes, hypertension and other medical factors are operative, in addition to psychological factors like personality, coping mechanisms, ego strength, and social factors like social support, environmental stressors have contributory roles.
Hence do not believe that if your environmental factors appear to be non contributory, you cannot suffer from depression. Please seek psychiatric consultation near you for better understanding and correct assessment of your problems. Hope this helps you..