... is a symptom of any of several sleep disorders, characterized by persistent difficulty falling asleep or staying asleep despite the opportunity. Insomnia is a symptom, not a stand-alone diagnosis or a disease. By definition, insomnia is "difficulty initiating or maintaining sleep, or both" and it may be due to inadequate quality or quantity of sleep. It is typically followed by functional impairment while awake.
In my case, staying awake for now particular reason until 6AM resulted in functional impairment while awake all right. I followed doctor's suggestions for proper sleep hygiene: reading, painting, watching TV, counting sheep ...the result was this: