More on sleep and time: the Letterman effect

Steve Higgins of Of Two Minds has a short post discussing recent research on, as the title says, Is TV changing our circadian rhythms? I think it’s another interesting factor to go into our subject-level dynamic systems model of time and sleep, after discussions by Daniel on Time Globalized and my earlier post on ‘Giant Sleep Machines’ and the Brain (which, now that I read it, sounds like a bit like a cheesy horror movie title).

Higgins discusses the article, ‘Cues for Timing and Coordination: Latitude, Letterman, and Longitude,’ by Daniel S. Hamermesh, Caitlin Knowles Myers, and Mark L. Pocock from the Journal of Labor Economics. I’ve searched for the original paper, and I can’t find it, even through the website of JLE; I’m not going to post this with the little ‘blogging about peer-reviewed research’ logo because I can’t really find the original. I suspect that it might be forthcoming; however, what I think is a working version of the JLE paper can be found through ANU here, and another working paper on a related topic by members of the team can be found here).

To get information about circadian rhythms, the research team used the Bureau of Labor Statistics’ American Time Use Survey (ATUS), focusing on how Americans divided time among their three most time-consuming activities: work, sleep, and television watching. Comparing the times people spent on these activities and their schedule with the time of sunrise and sunset, Hamermesh and his colleagues were ‘amazed how little daylight matters nowadays, and how much artificial time zones matter.’ (This quote and several others from a short article on the research at PsyOrg.)


The artificial cuing of diurnal cycle to the television schedule was stronger than the effect of the timing of daylight on people’s daily cycles. Those regions without daylight savings time — Arizona, Hawaii, Alaska, Indiana… (although the last may have changed as I was moving away in 2005, but see a piece on that and OPEC’s gain from daylight savings here) found their diurnal rhythm aligned more with the television schedule, which often led them to be more in alignment with neighboring areas which did go onto daylight savings times (and thus affected the timing of TV prime time).

As Hammermesh discusses, even though the prime-time television schedule is a ‘relic of the technology of radio transmission,’ created when signals could not be broadcast across the country, it now affects people’s daily lives in profound ways: ‘I lived twenty years in the Eastern Time Zone, I used to stay up until 11:45 p.m. to watch the monologue on The Tonight Show. Living in Texas, I typically turn out the lights at 10:45 p.m., when the monologue is done.’ I know how he feels. I used to be a night owl, often staying up quite late to work or watch the Letterman monologue; now in Australia, whether I like it or not, I’m on animal schedules, with the early feeding and removal of rugs for the horses anchoring a much earlier daily cycle thanks to wife’s affection for these animals.

The television schedule is a very simple way of thinking about effects across some pretty significant differences in scales of reality; technology affecting television programming (even after that technology is superseded), leading to media practices that impact individuals’ daily lives and basic decisions about scheduling, which then affects how much and what quality sleep they are getting and, through a long chain of events, not easy to anticipate but fascinating to trace, might affect all sorts of factors on biological scales, including things like obesity, stress-related illness, REM sleep patterns… The point is not ‘TV is bad for sleep’ but that a new technology (new on an evolutionary scale) can enter the dynamic system that helps to create diurnal patterns and significantly affect the resulting human behaviour.

One thought on “More on sleep and time: the Letterman effect

  1. Fascinating! In my practice, on sampling patients it seemed TV watching is a result of social isolation, irrespective of age. What do you think?

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