Valerian (Valeriana officinalis), is a natural herbal medicine that considers being naturally relaxing and calming since the ancient Greeks and Romans used it as a sedative.
Today you can find valerian as part of many night time herbal teas. In a tea, it goes well with other calming herbs, for example, a combination of lavender flowers and lemon balm; together with the other herbs, the mixture has a synergetic calming effect.
I love and recommend this one from Pukka:
Valerian may help with:
- Anxiety and associated difficulty of feeling calm and relax.
- Difficulty to fall asleep, waking up during the night and not getting a night of restful sleep.
- Postmenopausal symptoms-some clinical research shows that taking ground valerian root can help with hot flash severity and frequency. 
- Easing stomach cramps related to stress.
Valerian is a wonderful herbal medicine that is simple to use in a tea form or as a tincture.
When taking valerian by itself, you will notice its strong odour.
Valerian active ingredients and how it is working?
Active ingredients that found in valerian:
Valerian seems to act as a sedative on the brain and nervous system.
Valerenic acid and valepotriate constituents are the most famous active ingredients. Some valerian extracts are standardized based on the valerenic acid constituent. These extracts can be standardized to contain from 0.25% to 1% valerenic acid.
Multiple constituents are likely responsible for its pharmacological effects.
Final thoughts about valerian
Valerian might improve sleep quality without producing side effects. 
I would recommend you to try it first as a tea, and then if needed a stronger option as a tincture.
One of the options for a widely available valerian tincture is from A Vogel, a Swiss company that has a very good reputation for many years.
Remember that it can help not only for sleep but also for stress in general and for stomach cramps that related to stress.
I wish you all a calming day and a good night sleep!