Insomnia is most often a Vata aggravation, however any dosha may be involved. Insomnia may be the inability to get to sleep, frequently disturbed sleep or restless sleep with many dreams.
Deep sleep is time to re-visit your essential self, experience akasha, that divine nothingness from which all creation springs. This is an opportunity to remember your true self. Sleep is needed to refresh and revitalise us to face the challenges of this world. When you lay down your head take a moment to consciously leave your worries in the care of that universal consciousness at night. If you trust God with your problems at night you'll be much better equipped to deal with them again come morning.
Generally a warm, unctious, wholesome diet will help. Wheat, milk, ghee, root vegetables (excluding potato) should be taken, and stimulating foods including coffee and chili should be avoided. Warm sesame oil can be rubbed on the feet to ground Vata, and pull the energy down from the mind.
Try and bring some more routine to your sleeping patterns. Retire before ten and rise before six. Do some calming activities to wind down before bed, like breathing exercises, meditation, cleansing routines...avoid TV, loud music, newspapers and travel.
Pita type insomnia is characterised by dramatic dreams and hot emotions. Sleep tends to be broken too easily, especially between about midnight and 2AM. Kapha tends more towards lethargy, but can cause insomnia in cases of congestion or over eating, especially around 6-10 both AM and PM.