Passionflower (Passiflora incarnata) is one of my favourite herbs. Passionflower is beneficial for reducing stress and anxiety, and improving sleep. I use it in combination with Ashwagandha (Withania), Chamomile, Lavender, Lemon Balm, and Ziziphus. Combining with Magnesium is helpful in reducing muscle cramps, aches and pains, and good for overall relaxation.
A double-blind, placebo-controlled trial investigated the effects of Passionflower herbal tea on sleep quality. The study was measured using sleep diaries validated by polysomnography. Sleep quality showed a significantly better rating for Passionflower compared with placebo (t(40) = 2.70, p < 0.01).
Reference: Ngan A, Conduit R. A double-blind, placebo-controlled investigation of the effects of Passiflora incarnata (passionflower) herbal tea on subjective sleep quality. Phytother Res. 2011 Aug; 25(8): 1153-9.