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The Inner Clock Summary

Short Summary The Inner Clock explores the effects of our circadian rhythm, and how life in modern society doesn’t align with our biological clocks. The book suggests several solutions that allow us to get back in touch with our circadian rhythm and live happier, healthier and more natural lives.

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The Inner Clock Summary

The Deprivation Experiment

Lynne Peeples starts with an unlikely experiment: She spent 10 days in a bunker, cutting herself off from natural daylight. The bunker had no windows or clocks, forcing her to rely solely on her inner clock.

Depriving people of light is a common form of punishment and torture. You’ve probably heard about things like “the hole” in prisons, a form of solitary confinement in the dark. This shows that disrupting someone’s inner clock is serious enough to be used as punishment and torture. The same goes for depriving someone of dark, keeping them awake for days and exposing them to bright light.

The result of the experiment showed that her inner clock was out of sync. Devoid of sunlight and not able to rely on environmental cues, Lynne ended up eating dinner at 2:30am and going to bed at 4:30am, thinking it was 8pm.

Everything is driven by circadian rhythms, including your body temperature and when you use the rest room. Cut off from natural daylight, Lynne’s body functions and sense of time went haywire.

We need environmental cues such as day and night to keep our internal clocks aligned with the twenty-four-hour day. When external cues are missing or don’t match our inner clock, this causes problems.

Have you ever pulled an all-nighter? Then you’ve likely felt the effects of disrupting your inner clock. It turns day and night upside down. A similar thing happens when you experience jet lag due to long-distance travel.

Light Deprivation During the Day, Light Pollution at Night

Most of us spend a good amount of time living out of sync with our internal clocks. The main problem is that we experience daytime darkness coupled with light pollution at night.

During the day, we don’t get enough natural sunlight. Many people spend an excessive amount of time in buildings with no windows or exposure to natural sunlight. At the same time, we are deprived of darkness at night. Bright lights in cities, emitted from cars, streetlights, and buildings mess up our circadian rhythm.

New York is known as the city that never sleeps. This might quite literally be because of all the light emitted by the city all night long. Just think of the famous Times Square with all its screens and bright lights.

There is a social clock, which is the rhythm set by society. This includes when we are expected to show up to work or school. Even what time we have breakfast or dinner is dictated by our social clock. When governments impose time zones, the mismatch between the social clock and the alternation of day and night becomes even greater.

The social clock doesn’t match our inner clock: Lynne mentions garbage collectors not being able to see trash, or children getting hit by cars because they are walking to school while it’s still dark. These are all signs that our social clock is out of sync with our internal clock, which is influenced by the sun.

In Denmark and other places, some schools pushed back their start times to give teens a sleep boost. The results seem promising and are in line with Lynne Peeples’ research.

Some people suffer from seasonal affective disorder, commonly known as winter depression. During winter days, it’s common to have less exposure to natural sunlight. This is exacerbated by our social clock, and the fact that we spend a lot of time in buildings that limit natural sunlight.

Optimizing Your Circadian Rhythm

When our internal clocks aren’t properly calibrated, this has a negative impact on our lives. For example, sleep loss and disrupting the circadian rhythm hinders the performance of NBA players during long seasons.

It’s important to find your own circadian rhythm. Lynne points out that it’s not just about how many hours we sleep, but when we sleep and what happens before we sleep. By optimizing our daily schedule based on our circadian rhythm, we can become more productive. For example, our strength maxes out around dusk, which is when our pineal gland begins releasing melatonin.

Working out in the afternoon might be better than in the morning or evening.

There are several ways we can reset our inner clock. In an ideal world, we would listen to our inner clocks and not use alarm clocks. Human-made mechanical clocks can disrupt our circadian rhythm.

For most people, giving up alarm clocks is almost impossible. This is due to the social clock: The expectation that we show up to the office or school at a specific time. This lack of flexibility makes it hard to wake up when our inner clock is ready.

We should expose ourselves to bright, natural sunlight during the day and softer light at night. Tuneable LED systems could help counteract the mismatch between the social clock and our inner clock. While tuneable LED systems aren’t installed in most offices or buildings yet, there are several hacks you can use to reset your inner clock.

Get More Daylight, Eat At the Right Time and Minimize Exposure to Artificial Light

One hack that Lynne suggests is using a pair of high-quality blue-light-blocking glasses. These glasses will filter out unnatural light emitted from screens and devices, allowing your body to reset and use natural cues from the environment.

There are certain tools like f.lux, a simple application that will brighten and dim your computer screen based on the natural rhythm of day and night. Around dusk, f.lux switches to softer, amber-hued light and reduces blue light that might make your body think it’s still middle of the day.

F.lux is a great tool. If you’re going to stay up late and watch a movie or series, it will make all the difference. If you temporarily turn off F.lux after dusk, the light becomes so bright, it hurts your eyes and instantly wakes you up.

Taking naps can be beneficial, but Lynne recommends taking them in the morning and keeping them short so they don’t impact your circadian rhythm negatively.

Lynne has three rules to optimize your inner clock. First of all, she recommends getting thirty minutes of daylight first thing in the morning. Throughout the day, you should get as much natural sunlight as possible. After dusk, minimize exposure to artificial light. Finally, only eat when the sun is up.

Most of us probably break all three of Lynne’s rules every day. Try living by these rules for a week and see how it impacts your life. If you feel significantly better, your circadian rhythm might have been off.

It’s difficult to grasp the extent to which our inner clocks have been disrupted by life in modern society. But most of us can probably relate to lying in bed, glued to our screens, watching a series on Netflix, and having trouble falling asleep afterwards.

If you’re frequently tired, rely on coffee to get you through the day, have troubles falling asleep and feel like something is “off” about your day, it’s a sign that your circadian rhythm is out of sync. This means you should reset your inner clock and optimize your day so it matches your circadian rhythm.

Want to Save Action Steps From This Summary Of The Inner Clock?

Install f.lux or a similar tool on your devices to adjust your screen light and mimic day and night. This will keep your circadian rhythm in sync with the sun.

Get 30 minutes of sun light first thing in the morning. During the day, use every opportunity you can to expose yourself to natural sun light.

Avoid artificial lights at night and don’t eat after sunset. According to Lynne Peeples, this can help reset your circadian rhythm.

Complete This Summary Of The Inner Clock

Simple Quiz

What was the result of Lynne Peeples' 10-day bunker experiment?

What are the three rules Lynne Peeples recommends for optimizing your inner clock?

How can tools like f.lux help maintain your circadian rhythm?

The Inner Clock Review

We’ve all heard that sleep is important. But few people realize how out of sync their circadian rhythms are. We have constructed a world in which we are deprived of natural sunlight during the day, and polluted with artificial light at night. This leads to a life where many of us are tired, hit the snooze button multiple times and need coffee to get through the day.

At night, we then numb ourselves with blue light emitted from screens while munching on a late night snack, only to repeat the same broken cycle the next day. Deep down we know that something is wrong.

Lynne’s book is full of reminders about how important our circadian rhythm is, and how much we’ve been disrespecting it. Throughout the book, she shares plenty of research and a wealth of information to back up her claims. While reading the book felt a bit overwhelming at times, due to the sheer amount of information (including technical terms), this can be an important and life-changing read.

If you enjoyed this summary of The Inner Clock, and if you want to dive deeper into the many examples, stories and scientific research Lynne shares, you should definitely read the book.

Who would we recommend The Inner Clock summary to?

We recommend this summary of The Inner Clock to anyone who lives a coffee-fueled life. If you need to hit the snooze button multiple times, feel tired during the day and suffer from “winter blues”, you should take on Lynne Peeples’ advice and reset your inner clock.

About the author

Lynne Peeples is a science journalist with a master’s degree in biostatistics from the Harvard School of Public Health. She also has a master’s degree in journalism from New York university. Her writing has been featured in the Guardian, Scientific American, Nature and other publications.

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