5.13 Sleep aid/sedation
Traditionally, chamomile preparations such as tea and essential oil aromatherapy have been used to treat insomnia and to induce sedation (calming effects). Chamomile is widely regarded as a mild tranquillizer and sleep-inducer. Sedative effects may be due to the flavonoid, apigenin that binds to benzodiazepine receptors in the brain (
68). Studies in preclinical models have shown anticonvulsant and CNS depressant effects respectively. Clinical trials are notable for their absence, although ten cardiac patients are reported to have immediately fallen into a deep sleep lasting for 90 minutes after drinking chamomile tea (
47). Chamomile extracts exhibit benzodiazepine-like hypnotic activity (
69). In another study, inhalation of the vapor of chamomile oil reduced a stress-induced increase in plasma adrenocorticotropic hormone (ACTH) levels. Diazepam, co-administered with the chamomile oil vapor, further reduced ACTH levels, while flumazenile, a BDZ antagonist blocked the effect of chamomile oil vapor on ACTH. According to Paladini
et al. (
70), the separation index (ratio between the maximal anxiolytic dose and the minimal sedative dose) for diazepam is 3 while for apigenin it is 10. Compounds, other than apigenin, present in extracts of chamomile can also bind BDZ and GABA receptors in the brain and might be responsible for some sedative effect; however, many of these compounds are as yet unidentified.