A meta-analysis looking at the usage of hypnotics in older people found that although hypnotics did improve sleep with a number needed to treat (NNT) of thirteen (ie for every thirteen patients treated, one patient would experience improved sleep), they were associated with a range of adverse effects including ataxia, falls, daytime fatigue and memory impairment.[...] there is no outcome data easily available to clarify whether increased usage of zopiclone and triazolam and decreased usage of temazepam and nitrazepam resulted in better clinical outcomes.