Men and women aged 18 to 65 years of age who met
DSM-IV [18] criteria for primary insomnia ≥ 6 months
were eligible for screening. We limited the age of the
sample to those 18 to 65 because the incidence and
causes of insomnia are significantly different in both the
younger and older populations, thus requiring unique
studies to investigate the effect of chamomile in these
populations. We further operationalized insomnia as 7-
day sleep diary evidence of a total sleep time (TST) <
6.5 hours and sleep efficiency (SE) < 85% (total sleep
time/time in bed*100) on 3 or more nights.