Somesh shows loss of interest in most activities. He has estranged himself from family and friends, cannot sleep well at night and suffers from feelings of guilt. His symptoms are indicator of

Major Depressive Disorder

Major depressive disorder is defined as a period of depressed mood and/or loss of interest or pleasure in most activities, together with other symptoms which may include change in body weight, constant sleep problems, tiredness, inability to think clearly, agitation, greatly slowed behaviour, and thoughts of death and suicide. Other symptoms include excessive guilt or feelings of worthlessness.

Based on the described symptoms, Someshwar's condition is most likely Major Depressive Disorder (MDD).