This book was recommended by Daniel Pink in his book When—The Scientific Secrets of Perfect Timing, the subject of my last blog. Pink had six books he recommended in his Further Reading section. He said of this book, “You’ll learn more from this smart, concise work—organized into twenty-four chapters to represent the twenty-four hours of the day–than from any other single source.”
Given how I felt about When, that it could be life-changing in how I use my time and schedule certain tasks, how could I resist learning more? The subtitle to Internal Time is, Chronotypes, Social Jet Lag, and Why You’re So Tired. The author is Till Roenneberg, a German scientist but one with a real knack for making this subject understandable to a wide audience.
This book gets into more of the biology of our internal clock and the conflicts between social time, what we all live by, sun time, and everyone’s internal time. Some of the solutions I’ve arrived at by living in this body for a long time, I find have a biological reason for why they work.
Chronotypes
Because people naturally sleep at different times and for different durations, the sleep mid-point on free days (not determined by work schedule), is the way chronotypes are determined. For example, on a weekend, I will typically sleep from 9:30 to 6:30, putting my mid-point at 2:00 am. This puts me firmly in the lark category, that is, an early riser. There is no good or bad type of sleeper but the world views early risers favorably and late risers are considered lazy.
The worst example of the unfairness of this view is teenagers. Teenagers are owls. They can’t help it and it isn’t because they stay up late playing video games or posting on social media. For teenagers to perform well in school, high schools need to start much later in the day than most of them do. A few countries have adopted new schedules for high school but most still start school days far too early for teenagers. By the way, teenagers start to wake-up earlier at age 20; when they’re no longer teenagers.
Social Jet Lag
Social Jet Lag is the term the author coined for the conflicts between chronotype and the world we live in. Most people get up earlier in the day, to get to work on time, than they would naturally get up. In fact, 85 percent need an alarm clock to wake themselves. On free days, most people will sleep in. This conflict between social time—driven by work or school schedules—and one’s natural circadian rhythm, is a source of constant fatigue. My solution to this has been to maintain the same schedule on weekdays and weekends.
Shift Work
The worst conflict between natural chonotypes and work schedules is for those doing shift work, meaning working at night. People who work at night try to adjust by keeping a regular schedule and mimicking a normal schedule, but it really doesn’t work. Shift workers are awake when their body wants to sleep, eating when their body doesn’t want to and sleeping during daylight hours. Those doing shift work have far more health problems than those on a normal schedule.
Our Modern World
Our modern, industrialized lives create all sorts of problems for the bodies we live in. Because most of us don’t work outdoors, we get very little natural light. Even cloudy and rainy days provide lots of natural light to our bodies, which is how our internal clocks get calibrated. Most of us get less than one percent of the natural light we need. Instead, we live in the constant twilight of artificial light. Artificial light doesn’t replace the natural light but it will cause difficulty sleeping, especially if we’re exposed to screens in the evening.
Jet Lag
Have you ever noticed how it is easier to adjust to local time when traveling west compared to east? For example, when traveling to Europe, it is difficult to adjust to local time upon arrival. It is much easier when one travels from Europe back to the U.S. The reason is that it is easier to extend our day by exposure to natural light. Shortening the day, such as when traveling from the U.S. to Europe, can’t be done. My solution when traveling to Europe is to just stay awake for an extended period (usually 24 to 28 hours) and going to bed on local time. Exhausted but mostly adjusted to the local time.
Internal Time vs. Social Time
Our concept of social time, that is the 24-hour day and time zones, is a fairly new convention. Our species evolved and we are tuned to the sun. We get conflicts when these things get out of sync. For example, the switch to daylight savings time causes all sorts of productivity problems.
Time zones are only roughly correlated with sun time, because they are political. The most extreme example is China, which has one time zone while it should have four. Western China is 2 hours and 36 minutes off of sun time because they are on Beijing sun time.
Conclusion
All-in-all this is a terrific book. The writing style presents scientific concepts in stories and in 24 bite-sized chapters. If you’re interested in how time affects you and me, human animals, you’ll find this fascinating.
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