I have used viola odorata as a herb very often for colds and fevers in children, but not for this purpose.[sleep]
Insomnia. Preliminary clinical research in patients with chronic insomnia shows that placing 3 drops of a sweet violet extract in almond oil in each nostril at bedtime for 30 days improves chronic insomnia when compared with almond oil alone or placebo.
According to the Insomnia Severity Index (ISI), 73% of patients taking sweet violet oil were classified as having no insomnia at the end of the trial, compared with 16% of those taking almond oil or placebo (99647). Another small clinical study in patients with mild to moderate primary chronic insomnia shows that intranasal application of 2 drops of an herbal oil containing equal parts of oil extracts of sweet violet aerial parts, saffron stigma, and lettuce seed in sesame oil twice daily for 8 weeks improves both ISI and Pittsburgh Sleep Quality Index (PSQI) scores by 4-5 points at 4 and 8 weeks, compared with 1-2 points in those receiving sesame oil alone (106576). It is unclear if these effects are due to sweet violet, other ingredients, or the combination.
The tincture is hard to find
I found it on eBay https://www.ebay.com/itm/124650348335
Maybe the homoeopathic pharmacies also sell it in Israel.[night time, could not ask them]