Improving sleep. Poor sleep habits such as spending too much time in bed or going to bed at different times on different days can cause difficulty with sleep. So can anxiety, noise, light in the bedroom. Improving sleep habits by going to bed at the same time every night, getting up every morning about 7 hours later whether or not you slept well, and avoiding naps, might help. If it does not, get treatmnent.
Try sleeping less. There are different insomnia patterns, with different causes and treatments. If your primary problem is trouble falling asleep at the beginning of the night, try sleep restriction therapy. Get up at the same time every day, but start by spending only five hours in bed per night. When you've slept at least 4.5 hours two nights in a row, increase to 5.5 hours, etc., until you are up to 7-8 hours.
Sleep ; meditation. It's possible for the extended silence of a 10 day vipassana retreat to allow many things to come up for review -- things that your normal day-to-day busyness might suppress. After all, mindfulness is about waking up -- rather than going through our lives asleep. A psychotherapist familiar with meditation may be helpful to you now, in exploring your own individual experience. Many do this work.