Hops

Hops (Humulus lupulus) is plant from which the strobiles (female flower) are used for a variety of purposes including as a sleep aid. Hops is rarely available in single-herb preparations and is usually combined with valerian, lemon balm, passion flower, skullcap, and/or kava. The main constituents of hops are the bitter acids, lupulone, and humulone [73, 74]. Constituents of hops extract have been shown to bind to melatonin and serotonin receptors, although it remains unknown whether this binding produces receptor agonist or antagonist effects [75]. Hops has been shown in animal studies to exert sedative effects, primarily through the alpha-bitter acid constituents [74, 76].

No studies have specifically tested hops in older adults with sleep disturbance. The product most commonly tested is the valerian–hops combination, ZE 91019 (Alluna^®). Two 4-week placebo-controlled, double-blind RCTs of this product showed no significant differences from placebo on self-report or PSG sleep outcomes in persons with insomnia [61, 77]. A double-blind RCT comparing 2 weeks of valerian–hops to the benzodiazepine, bromazepam, in persons with insomnia showed significant improvement on a sleep quality scale over time and no significant difference between the two treatments [78]. Although this study showed equivalence between valerian–hops and a benzodiazepine, the magnitude of change was small and there was no placebo group. Finally, a recent placebo-controlled, double-blind RCT comparing a valerian–hops combination (ZE 91019) to valerian alone (ZE 911, the same valerian in the ZE 91019 combination) for 4 weeks showed significant reduction of self-reported sleep latency with valerian–hops but not valerian compared to placebo [79]. Neither treatment significantly affected total sleep or wake times. Overall, evidence from combination preparations suggests that hops may have some sedative properties, at least in combination with valerian, but improvements in sleep tended to be non-significant when compared to placebo and in some studies placebo effects could not be ruled out. In summary, the findings in one study showed that valerian–hops was associated with a large reduction in sleep latency [79], but overall evidence does not currently support the efficacy of hops (used in combination with valerian) as a sleep aid.

Potential side effects from hops are mostly from anecdotal evidence and include upset stomach, topical or respiratory allergy, nervousness, or depression [78, 80]. Hops has also been reported to have estrogenic effects and should be avoided for history of estrogen receptor-positive breast cancer