Early birds and night owls are born, not made. Sleep patterns may be the most obvious manifestation of the highly individualized biological clocks we inherit, but these clocks also regulate bodily functions from digestion to hormone levels to cognition. Living at odds with our internal timepieces, Till Roenneberg shows, can make us chronically sleep deprived and more likely to smoke, gain weight, feel depressed, fall ill, and fail geometry. By understanding and respecting our internal time, we can live better.
Internal Time combines storytelling with accessible science tutorials to explain how our internal clocks work – for example, why morning classes are so unpopular and why "lazy" adolescents are wise to avoid them. We learn why the constant twilight of our largely indoor lives makes us dependent on alarm clocks and tired, and why social demands and work schedules lead to a social jet lag that compromises our daily functioning.
Many of the factors that make us early or late "chronotypes" are beyond our control, but that doesn't make us powerless. Roenneberg recommends that the best way to sync our internal time with our external environment and feel better is to get more sunlight. Such simple steps as cycling to work and eating breakfast outside may be the tickets to a good night's sleep, better overall health, and less grouchiness in the morning.
1. Worlds Apart
2. Of Early Birds and Long Sleepers
3. Counting Sheep
4. A Curious Astronomer
5. The Lost Days
6. The Periodic Shift Worker
7. The Fast Hamster
8. Dawn at the Gym
9. The Elusive Transcript
10. Temporal Ecology
11. Wait until Dark
12. The End of Adolescence
13. What a Waste of Time!
14. Days on Other Planets
15. When Will My Organs Arrive?
16. The Scissors of Sleep
17. Early Socialists, Late Capitalists
18. Constant Twilight
19. From Frankfurt to Morocco and Back
20. Light at Night
21. Partnership Timing
22. A Clock for All Seasons
23. Professional Selection
24. The Nocturnal Bottleneck
Till Roenneberg is Professor at the Institute of Medical Psychology at the Ludwig-Maximilians University, Munich.
"Internal Time is a cautionary tale – actually a series of 24 tales, not coincidentally. Roenneberg ranges widely from the inner workings of biological rhythms to their social implications, illuminating each scientific tutorial with an anecdote inspired by clinical research [...] Written with grace and good humor, Internal Time is a serious work of science incorporating the latest research in chronobiology [...] [A] compelling volume."
– A. Roger Ekirch, The Wall Street Journal
"Time really is of the essence, says medical psychologist Till Roenneberg. By neglecting our body clocks – which rarely run in synchrony with the crazily cranked-up pace of modern life – we can develop 'social jetlag', endangering our health and careers. Roenneberg has built his book on decades of research in everything from fungi and single-celled organisms to humans. In brilliantly minimalist terms, he explains the temporal mismatches behind teen exhaustion, early birds and night owls, and sleep phobia."
"In Internal Time, Till Roenneberg, a chronobiologist at the Ludwig-Maximilians University in Munich, Germany, takes readers on a journey through this mysterious area of science. He explores why some people are larks and others owls, why jet lag can be so debilitating to travelers, and why teenagers struggle to get out of bed in the morning [...] Roenneberg is a knowledgeable guide, with a talent for making difficult concepts clear and convincing [...] This is a fascinating introduction to an important topic, which will appeal to anyone who wishes to delve deep into the world of chronobiology, or simply wonders why they struggle to get a good night's sleep."
– Richard Wiseman, New Scientist
"Till Roenneberg's book is an engaging and informative layman's introduction to circadian science and its implications for contemporary humans [...] By integrating quality scientific exposition with well-rounded human vignettes, Roenneberg's book shows how sophisticated human behaviors arise partly from our embodied earthly nature."
– Greg Murray, Times Higher Education
"Internal Time made me think deeply about what it means to be a time-bound organism: about the ways we live in time and the ways time lives in us. It is, in an unusually literal sense, a book about what makes us tick."
– Kathryn Schulz, New York Magazine
"After reading this book, I've never more appreciated a good night's sleep [...] This is a fascinating, charming and eye-opening book about the sleepless menace lurking just below the surface of modern life."
– Pumpjack Press
"A brilliant book."
– William Leith, The Telegraph
"Fascinating [...] Other books have dealt with our biological clocks, but Roenneberg focuses on the ways in which societal pressures seem to be leading us to disregard our clocks, at considerable cost."
– Rob Dunn, Wilson Quarterly
"This is a wonderful book from a gifted scientist, thinker and writer that provides the reader with the rare opportunity to discover something new about themselves and the world in which they live."
– Russell G. Foster, University of Oxford
"Internal Time is an accessible, up-to-date overview of a subject that is important to all of us. With its remarkable depth and breadth of coverage, this book should be of interest to a wide and diverse audience."
– Martin Zatz, Editor, The Journal of Biological Rhythms