Do You Live Where You Should Sleep More?

How much we sleep could relate to where we live.

You can see Mountain Time Zone people seem to go to bed before everyone else:

This is the story.

Time Zone History

When the railroads first divided the U.S. into time zones, they just wanted consistency. After all, arrival and departure times had to be in sync across the land.

TED Ed did a 3 1/2 minute version of time zone history. Do take a look:

Time Zone Impact

However, according to a recent paper, once we solved one problem with time zones, we created others. Yes, our clocks could be synchronized. But not necessarily our bodies. Called social jet lag, we wound up with a disconnect between our biology and our schedule.

Body Time

Some of our physiology responds to light and dark. When we produce more melatonin and cortisol can depend on when the sun sets. Our Vitamin D accumulation relates to sunshine. It’s all just a part of our built-in rhythms.

So, when we have later sunset times, our body responds:

Clock Time

Then though we have clock time. Because of the width of a time zone, the sun sets earlier and then later as it moves westward. Responding, the people at different ends of the time zone go to bed at different times, eat at different times, and schedule their evenings differently.

The problem though is that we have to wake up at clock time. Some of us have to be at work before 7:30 a.m. We have to take children to school early. Still, if our body clock nudged us toward going to bed later because of the later sunset then we got less sleep. The nightly sleep loss from a later bed time and early wake up could be as much as 36 minutes.

The Impact

Combined the impact of the body and clock time disconnect is billions in healthcare expenses and lost productivity. A statistically significant proportion of people with inadequate sleep are obese (5.6%). Less sleep also relates to a higher incidence of diabetes, coronary disease, and breast cancer. At work, our productivity shrinks. Cognitively, our performance is less than optimal. We take more days off from work. Even per capita income is less.

You can see the average sleep time (especially on weekdays) of a sample of approximately 18,000 individuals. The ideal is 7 to 8 hours:

And some other data from the study:

Our Bottom Line: Tradeoffs

When we synchronized our clocks, we created a tradeoff. Of course it made sense to eliminate local time where every town could decide the hour of the day. But there was a cost that we could call social jet lag. It’s the price we pay when our schedules clash with our physiology.

As a night owl, i feel compelled to add that the cost might be less for those of us who enjoy the extra evening hours.

My sources and more: This Washington Post article reminded me it was time to return to the impact of time on our health. From there, if you want to see the original study (as did I) do go to this paper.