There are a number of things that can cause insomnia including stress, shift work, alcohol and noise. If you are always tired during the day then you probably do not get enough sleep.
You can implement a number of things to help with your sleep issues. If they do not work and it is affecting your life then you should contact your GP.
CBT-I is an approved method for treating insomnia without the use of medication. Aiming to alter the patients sleeping pattern as well as changing the misconceptions about sleep and insomnia that could otherwise continue indefinitely.