Geeking Science: Internal Clocks

Image courtesy of Nasa

Our body has a clock. A crazy accurate circadian rhythm clock that hates stupid changes like daylight savings, which happens on November 4, and traveling by airplane, leaping ahead on the planetary rotation cycle. Or any of the other dozen things we human do instead of sleeping with the day-night cycle of the planet.

For each hour shift, our bodies need a day to recover. Until the body is reset through signals from our day star and temperature, we drag and snap and have ever so slightly poorer health.

The real question isn’t how long does it take to recover, but how do we recover at all? Scientists are studying this question for a lot of reasons: insomnia, health issues affecting sleep, night occupations, shift workers, and, for the purpose of this post, settling other planets. Think about it. Mars’ daylight cycle is 24 hours and 39 minutes, not a clean 24. Jupiter’s moon Europa is three and a half days. Saturn’s moon Titan, the best candidate for a way-station before the Oort cloud and The Big Trip to visit other planetary systems, is nearly sixteen days. The Moon, four weeks. Venus, over 116 days, one-third of an Earth year.

Normally our bodies would recover in a day when changing a time zone. Imagine if every single day shift things nearly 40 minutes. If we live on the extra-forty-minute-day of Mars, and not in tunnels set to an Earth cycle, we and our neighbors will suffer perpetual jet lag symptoms of: disrupted sleep cycles, fatigue, difficulty concentrating and functioning, digestive issues like constipation or diarrhea, and mood changes. Long-term health issues increase since the regular healing cycle of the body is disrupted, increasing cancer and heart issues. 

The human clock is not a perfect 24-hour clock, any more than an Earth day is always a perfect split of 12 hours day-12 hours night. We are built to handle seasonal shifts, including the up-to three minute shift in daylight per day, by resetting the clock with the sun every morning. (Staying up late at night staring at glowing screens screws up this resetting. Just saying, marathon Netflix watchers.) According to a recent study, our biological clock runs 24 hours and 11 minutes. with a 16-minute variation by individual.

We got wiggle room for small seasonal shifts. We can even make big shifts when required. The question is what happens when the entire planets is pulling a daylight saving’s change every single day. Humans are built for Earth; our internal clock screams it “Tick, tock.”

And yet. And yet.

We were built for Earth, but we are not going to stay here. Tick, tock.



Human Biological Clock Set Back an Hour. William J. Cromie. Harvardgazette. July 15, 1999. (last viewed 11/23/2017:

The Hidden Impact of Jet Lag on Your Body. Sarah Digiulio. Huffpost. April 15, 2016. (last viewed 11/23/2017:

Watch Out: Daylight Savings Time May Cause Heart Attack Spike. Laura Geggel. LiveScience. March 7, 2005. (last viewed 11/23/2017:

Welcome to Mars! Enjoy Perpetual Jet Lag Under An Eerie Red Sky. Rebecca Boyle. FiveThirtyEight. March 7, 2017. (last viewed 11/23/2017: