Valerian root definitely has known relaxing and/or sedative effects. Simply harvesting the stuff causes sleepiness although I am not sure if the effective pathway is by touch or airborne.
You may need to adjust your dosage higher (slowly) to feel an effect and a lack of strict standardization within the holistic supplement world means differing brands if the same overall dosage may yield significantly differing effective dosages.
My experience has been that with an effective dose Valerian works (currently I take four 470 mg capsules) however like with the stimulants I seem to build up a tolerance.
Currently when the stimulants build up and leave with with bad insomnia I take the Valerian with 3-6 mg of melatonin and 1-2 tablets of low dose of magnesium.
WARNING on the magnesium: Magnesium is very cardiovascular interactive and may be counter indicated if you have any form of cardiac, cardiovascular and/or blood issues that you are or have been treated for. Please discuss with your physician first if this is the case.