[tz] Daylight saving and heart attacks

[Paul Eggert]

On 6/24/19 6:51 PM, Tim Parenti wrote:
> On Mon, 24 Jun 2019 at 20:06, Paul Eggert <eggert at cs.ucla.edu 
> <mailto:eggert at cs.ucla.edu>> wrote:
>
>     One way to tease out the effects of daylight saving time is to
>     look at
>     the health records of people near a time zone boundary, as you get a
>     one-hour civil-time difference for free.
>
>
> This could, of course, be confounded somewhat in boundary cases where 
> there are mixed economic ties.

Yes, but another way to measure health effects is to look at the 
difference between local time and local mean time (i.e., how much our 
clocks are advanced relative to their "natural" time) as a continuous 
variable that increases gradually as you move across the time zone. Gu 
et al. studied cancer risk in the US this way, and found that your risk 
of getting cancer increases as you move east to west across a time zone. 
In other words, the earlier in the morning that you are awakened 
artificially, the more likely you'll get cancer. This result can't be 
explained by artifacts near time zone boundaries.

Because this effect has been found in multiple countries, I expect that 
permanent daylight saving time would significantly increase cancer 
incidence in the US.

Gu F, Xu S, Devesa SS et al. Longitude position in a time zone and 
cancer risk
in the United States. Cancer Epidem Biomarkers Prev. 
2017-08-01;26(8):1306-11
http://dx.doi.org/10.1158/1055-9965.EPI-16-1029