Research conducted by Irwin, Bjurstrom and Olmstead (2016) aimed to study the relationship between sleep and cocaine and alcohol use.<sup>8</sup> In this study, the participants were individuals who has previously been dependent on these substances but were now in the early stages of abstinence.<sup>8</sup> Polysomnographic sleep measures were recorded to determine sleep continuity, Stage 3 sleep and rapid eye movement (REM) sleep.<sup>8</sup> In this study, sleep continuity included the total sleep time, sleep latency, which is the time required to transition from full wakefulness to sleep, sleep efficiency and wake sleep onset.<sup>8</sup> Moreover, Stage 3 sleep was characterized by slow wave sleep (SWS), which consists of very slow delta waves in combination with smaller, faster waves in the brain.<sup>8</sup> These measurements were then compared to the controls, which were patients that had no medical history of any mental illnesses or disorders.<sup>8</sup> Although the results of the study indicated sleep continuity is not impacted by drug or alcohol use, the study did show that there was a decrease in Stage 3 sleep among both alcohol and cocaine-dependent patients.<sup>8</sup> The results also indicate that loss of Stage 3 sleep occurs at an earlier age among the cocaine-dependent patients, in comparison to the alcohol-dependent patients.<sup>8</sup> In addition, the amount of REM sleep increased among both groups of participants in comparison to the controls.<sup>8</sup> Therefore, this study demonstrates that alcohol and cocaine have an impact on sleep disturbances.