Historically, many essential oils have been valued for their ability to relieve anxiety, tension caused by stress, insomnia, and similar issues. A partial list of some oils generally regarded as calming, relaxing, uplifting (but not stimulating), or stress-relieving include:

~ Atlas Cedarwood
~ Clary Sage
~ Geranium
~ Lavender
~ Lemon Balm
~ Mandarin
~ Petitgrain
~ Rose
~ Ylang Ylang

via Aromatherapy for Stress Insomnia Anxiety.