In Ayurveda, there are two main causes for insomnia, namely unbalanced body elements and eating habits, and systemic dryness.

Other then the 2 main cause’s insomnia can also be brought on by stress, excessive  of a regular routine.

Simple Remedies for Insomnia:

Prescribed medicated oil application for head before bath is helpful.
Adding the following herbs like calamus, Bramhi, Amalaki (Indian goose berry), Aniseed, Celery, Sarpaganda, Aswaganda, Valerin in your diet are useful in insomnia
In the early stages of the problem there’s no need of medication, cooling and calming the body is the recommended line of treatment. At this stage some simple therapies can be followed like:
 
Abhyangam: (Oil massage):
Soft oil massage induces good sleep and blood circulation; the oil application should be mainly to the head, face, earlobes and foot.

Shiro dhara: (oil dripping for forehead):
Dripping of Luke warm oil over the forehead is good not only for headache & stress but also insomnia.