Hi, your history suggests that you have milder form of sleep disorder hence we cannot put you into particular medical condition. There is a delayed onset of sleep and interruption of sleep which may be due to committed work, success, stress, unusual happenings make you anxious and it will keep you awake and will lead to delayed onset of sleep.
The therapy for this condition includes retaining of normal circadian rhythm by non-pharmacological therapy which includes; Photo therapy, maintenance of sleep hygiene. You need to go for morning exercises and work out which will make you fresh and active all day and tiredness at the end of day will help you to induce sleep naturally. Avoid stress and go for relaxation methods.
Pharmacological therapy includes short course of appropriate sedatives and Hypnotics against prescription. Non-benzodiazepines are effective in delayed onset sleep disorder and help to initiate the sleep.
I suggest you to consult physician. Take care and regards.
Are you taking any meds regularly ? Are you tired enough, what is your evening routine , how late do you eat ? Could be varying reasons , can you give us an idea of your routine before bed ..