It looks like the interview excerpt refers to the following passage in the book "Why We Sleep" by the interviewee Matthew Walker: "The irony is that many indiv

It looks like the interview excerpt refers to the following passage in the book "Why We Sleep" by the interviewee Matthew Walker: "The irony is that many individuals experience only a slight increase in “sleep” from these medications, and the benefit is more subjective than objective. A recent team of leading medical doctors and researchers examined all published studies to date on newer forms of sedative sleeping pills that most people take. They considered sixty-five separate drug-placebo studies, encompassing almost 4,500 individuals. Overall, participants subjectively felt they fell asleep faster and slept more soundly with fewer awakenings, relative to the placebo. But that’s not what the actual sleep recordings showed. There was no difference in how soundly the individuals slept. Both the placebo and the sleeping pills reduced the time it took people to fall asleep (between ten and thirty minutes), but the change was not statistically different between the two. In other words, there was no objective benefit of these sleeping pills beyond that which a placebo offered. "Summarizing the findings, the committee stated that sleeping pills only produced “slight improvements in subjective and polysomnographic sleep latency”—that is, the time it takes to fall asleep. The committee concluded the report by stating that the effect of current sleeping medications was “rather small and of questionable clinical importance." The study cited for this passage on the book is a meta-analysis (or a study of multiple studies, as you might already be aware) [0]. The relevant excerpt from the study is: "All 13 studies included comparisons of at least one of our primary outcomes. Ten studies (22 comparisons) assessed polysomnographic sleep latency and seven (11 comparisons) assessed subjective sleep latency. The eight remaining secondary outcomes appeared in fewer studies: four studies (seven comparisons) assessed subjective total sleep time, two (two comparisons) assessed total polysomnographic sleep time, four (six comparisons) assessed subjective number of awakenings, three (four comparisons) assessed polysomnographic number of awakenings, two (four comparisons) assessed subjective sleep quality, three (five comparisons) assessed sleep efficiency, three (three comparisons) assessed polysomnographic waking after sleep onset, and one (one comparison) assessed subjective waking after sleep onset." Polysomnography is defined as followed by the Mayo Clinic [1]: "Polysomnography, also called a sleep study, is a comprehensive test used to diagnose sleep disorders. Polysomnography records your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study." TL;DR: It looks like the meta-analysis of multiple studies, included studies that examined "brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements during the study." [0] https://www.bmj.com/content/345/bmj.e8343 https://www.bmj.com/content/345/bmj.e8343 [1] https://www.mayoclinic.org/tests-procedures/polysomnography/about/pac-20394877 https://www.mayoclinic.org/tests-procedures/polysomnography/...