Tryptophan is an essential amino acid. Serotonin is produced in the body from tryptophan and serotonin has anti – depressant property. Serotonin is a hormone that transmits signals between nerve cells. But its anti – depressant effect is not fully elucidated. Zoloft and citalopram have proven efficacy as anti – depressant effect. All anti – depressants interact with warfarin. But both Zoloft and citalopram have least chance of interaction with warfarin and these two are anti – depressant of choice in patients who are also taking warfarin. All anti – depressants cause drowsiness to a variable extent. You are hypertensive so you can continue with Zoloft. You can take a trial with tryptophan also. You can also try with yoga, workout in gym and head massage. These are natural anti – depressant. But If you currently take a prescription antidepressant, do not stop taking it without consulting your doctor. Do not haphazardly replace your current medication with natural remedies. Thanks