One study was published in a peer reviewed journal, SLEEP, that looked at the efficacy of Night Owl – Sleep Coach. The sleep log data of 157 users, who had completed at least 14 sleep logs, was anonymized and then analyzed for efficacy. Using paired-samples t-tests, sleep log data from a user was compared to that same users previous sleep log data and the differences were recorded. Of users who had completed at least 3/6 components, significant differences were shown in sleep onset latency, minutes awake after sleep onset, sleep efficiency, and total sleep time.
(Harbison et al., 2018. https://academic.oup.com/sleep/articlepdf/41/suppl_1/A155/24751464/zsy061.407.pdf)