Crozet Annals of Medicine: It’s 5 O’Clock Somewhere


A headline grabbed my eye the other day. It was a glorious early spring day and as if to highlight the emerging warmth and daffodils, the U.S. Senate announced it had just passed the “Sunshine Protection Act.” Hooray! I love sunshine!

But wait, what were they protecting it from? Rain? Clouds? Night? I did not know about the threats to sunshine. So, I read the article. Turns out the Senate had, through a parliamentary trick passed a bill making Daylight Savings Time permanent. The House of Representatives still has to vote on it and hopefully the idea will gather more scrutiny there because there are important medical reasons why this is a bad idea.

Daylight savings time (DST) began in the U.S. during World War I as an energy saving measure. It has never been clear whether it saves energy, but the disruption to our lives and health have long been clear.

Humans have a biologically programmed sleep–wake cycle that is slightly longer than 24 hours. Without the outside stimulus of light, we would sleep a little later every morning and go to sleep a little later each night. Over time we would end up sleeping all day and being up all night before continuing the cycle back eventually to the reverse in an endless loop. This is called Non 24-Hour Sleep Rhythm Disorder.

Fortunately, this doesn’t usually happen, and we can thank our third eye for that. This “third eye” is deep in our brain and is called the pineal gland. The pineal gland detects light via meandering neurologic pathways from the eyes and responds by producing melatonin, the “sleep hormone” at night. The light from the sun stimulating the pineal is vital to keeping this cycle working at the correct times. When it goes awry the Non 24-Hour Sleep Rhythm Disorder occurs.

While rare in most of the population, Non 24-Hour Sleep Rhythm Disorder afflicts roughly half of all blind people. For sighted people, the sun resets our biological clock every morning backwards to a 24-hour sleep wake cycle.

Most of our biologic processes are tied to this sleep-wake cycle, or what is known as circadian rhythms. Blood pressure regulation, blood sugar regulation, stress hormones, body temperature, immune system function, alertness, cognitive abilities and many more are all governed by the 24-hour sleep wake cycle. Mess with it at your peril. Consider the evidence.

A study published in 2020 in Current Biology found that in the first week after the spring transition to DST, when dawn comes later, fatal car accidents increase by 6%. While most pronounced in the mornings, it holds true even in the afternoons. It seems to more to do with disruptions to our circadian rhythms with subsequent decreases in our alertness than with the ambient light while driving. This is more pronounced the further west you go in each time zone. A similar increase does not occur during the “fall back” to Standard Time each Fall.

In fact, living the furthest west in any time zone also raises your risk of most cancers by 3-4%. The later the sun rises relative to clock time, the more your circadian rhythms are disrupted, which seems to result in more cancers. This is seen in night shift workers as well, most of whom have some form of Sleep–Wake disorder.

A 2015 study in Sleep Medicine found that the rate of stroke rose 8% in the two days after the DST transition with rate rising by 20% in people over 65. Heart attacks increase as well.

Teenagers are particularly prone to the negative impacts of DST. The onset of puberty brings changes to adolescents’ sleep-wake cycle. Their melatonin rises later in the evening making them prone to staying up later and sleeping-in longer. Most American teenagers are chronically sleep-deprived due to this, and the too-early start times of most high schools. DST exacerbates this even further. Psychologists warn that this is contributing to high rates of depression and anxiety in adolescents.

 In a revealing study in 2006, researchers looked at the SAT scores of Indiana high school students from 1997 to 2006. In that period of time Indiana did not have universal DST; individual counties were free to switch or not. The students in counties that had DST scored 16 points lower on the SAT’s than students in counties that kept Standard Time.

So why have we kept switching back and forth? Well, most businesses like DST, and they lobby Congress for it. An extra hour of daylight after work means people get out more, shop more, eat out more, etc. But we can’t really stay on DST year-round; in the winter sunrise in the westernmost regions of the time zones would be as late as 9 a.m. or even 10 a.m. in Alaska. School would start in the dark as would most workplaces. And with the shorter day lengths, it would be dark sooner in the evenings as well. So, in the winter we reset the clocks so that our awakening is closer to the start of daylight. Our bodies like this. Sleep researchers, represented by the American Academy of Sleep Medicine, are unanimous in advocating for permanent Standard Time as the most salubrious solution to keeping time. 

But most Americans like DST. A recent poll shows 44% in favor of permanent DST while 35 % liked the twice-yearly clock switching and only 13% wanted permanent Standard Time. And yet when we switched to permanent DST in 1974 to combat the gas crisis, Americans hated it and voted overwhelmingly to scrap it. The dark mornings were just too depressing. Also, it did not save any energy. 

It seems when people say they like DST what they really mean is they like summer with its longer hours of sunlight. DST itself doesn’t actually provide any more hours of sunshine after all.

That seems too obvious to even mention, but our lawmakers may need a reminder. Senator Tommy Tuberville (R-AL) said in a speech supporting the Sunshine Protection Act, “Let’s give Americans something to celebrate: longer days and more sunshine.” I marvel at the audacity of Congress, taking credit for creating summer itself. 

Senator Patty Murray (D-WA) added a bipartisan note of inanity saying, “Americans want more sunshine and less depression.” Yes, Americans do want more sunshine, and we deserve it too!

But the ultimate Congressional hubris was voiced by Rep. Jan Shakowsky (D-IL) who mused, “I was pretty surprised we had the power to change time itself.” Wow. 


Please enter your comment!
Please enter your name here