Anxiety like any emotion is a necessary survival factor. No anxiety means no apprehension of potential danger. Nature does not encourage this. Anxiety is not a negative emotion unless it overpowers normal function.
Anxiety can be acute or chronic: acute anxiety will occur in relation to frightening or worrying events, chronic anxiety is persistent and pathological if it has no logical foundation. Being anxious about, for instance, a loss of job or failing relationship is not wrong and would be best dealt with through counselling and some basic homeopathic remedies.
Avoid stimulating foods at night, especially cheese, chocolate and spices.
Alcohol can offer a temporary relief but may lead to persistent use and possible dependence in the same way that a drug such as a beta-blocker might. Avoid both.