The Nexium (esomeprazole) should be taken at least 1 hour before eating, so I would separate it from your multivitamin. Other than that you may take these medications together. Just be aware of a few interactions. The Nexium (esomeprazole) can increase the effects of the diazepam. Taking diazepam with a sedating antihistamine can cause increased sedation, dizziness, and confusion. It was difficult to find what interacts with the Kanna. I would just use caution because it too can make you sedated. It is ok to take the valerian if you do not take the diazepam (again, only when going to sleep because it is sedating). Just be sure not to take the valerian and diazepam together. They are believed to work in a similar way in the brain.
Your doctors are giving you pills to help you sleep, but are not looking to the cause of your sleeplessness. I suffered from insomnia for 30 years. No one looked for a cause. I found what it was accidentally when I developed a craving for clams. I needed iodine. I now take iodine supplements and sleep like a normal person. A simple solution to a serious problem. Try to get your doctors to investigate your insomnia, and don't let them pawn you off by telling you it is emotional, or that you are under stress, or that it is all in your head. Believe me, you have my sympathy. But doctors who practice psychology 101, instead of practicing medicine, do not.
Much appreciated. Thanks very much. Yvonne xx