Being relaxed is different to de-stressing. When someone dies it is stressful if you care about them and you often question your own mortality etc.
Lavender is relaxing, in the sense of providing comfort for sleep. I have a cuddly lamb that you can heat up and it has lavender in it and I hug him at night (yes it is a boy lamb) and he smiles with his cute little face and I can smell the mild scent and close my eyes and enter into blissful sleep.
Alas he is not with me on tour and I miss him and am not sleeping so well. I'll have him back in my arms again on Saturday!!!
p.s. Are you sure your friend was not giving you heather?