No single sleeping pill stands out as the best, according to a U.S. review of the newer sleep aids on the market.The researchers reviewed 141 studies of the sleeping pills Sonata, Ambien, Lunesta and a Canadian brand called Imovane. These are all considered newer sleeping aids and are commonly prescribed for insomnia in place of older benzodiazepine sleeping aids such as Halcion, ProSom and Restoril.The OHSU review concluded that these newer sleeping pills were more effective than placebo pills at treating insomnia symptoms and that “although there are some differences between the drugs on some outcomes, no one drug appeared to be consistently superior."For example, Sonata seemed better than Ambien at putting people to sleep quickly, while people taking Ambien slept longer and reported having a better quality of sleep than people who took Sonata.