“…And only a few randomised controlled studies [34,35,36,37] have evaluated the effects of MBIs among adults with chronic insomnia, although most of them were limited by their study design including small sample sizes ( n = 30-60) [34,35,36,37], including adults only in a certain age range [35,36] or having a short follow-up period [35,36,37]. As a result, although preliminary promising findings favouring MBIs in improving sleep quality or reducing insomnia severity were suggested [34,35,36,37], studies with a larger sample size which are adequately powered are needed to offer a more definitive conclusion on the effectiveness of MBIs on chronic primary insomnia.…”