In a 2020 review, it shows evidence of nine randomized clinical trials exploring the effects of passionflower in neuropsychiatric disorders.  The literature data suggest that the passionflower itself, as well as its preparations, helps reduce stress and can therefore be helpful in the treatment of insomnia, anxiety, and depression.

A 2020 article on Effects of Passiflora incarnata Linnaeus on polysomnographic sleep parameters in subjects with insomnia disorder presents a double-blind randomized placebo-controlled clinical study where passionflower was investigated in the use of treating insomnia.  110 adults participated and they received either passionflower extract or the placebo for 2 weeks.  The length of sleep was longer in the passionflower participants in comparison to the placebo.  It was recorded that sleep efficiency and wake after sleep onset significantly improved after 2 weeks in the passionflower group but there was no difference compared with the placebo group. 

Evidently the study demonstrated the positive effects of passionflower on objective sleep parameters.