How can i learn to relax without using drugs like anti depressants?

Psychotherapy: Working with a psychotherapist is one way. You can focus on your individual concerns and learn new ways of coping with them, or hopefully resolving them. It's good to have a professional guiding you as you do this. On your own you can also learn to meditate, do breathing exercises, yoga, tai chi, qi gong, and other methods. You can stay away from caffeine and other stimulants, also.

Meditation: Can do wonders for reducing stress and related hormones, anxiety, and blood pressure. Instruction is required and consistent practice is optimal. Research over many decades is incontrovertible.