Winner of a British Medical Association Book Award
A Brain Pickings Best Science Book of the Year

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 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, Wall Street Journal

“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

In three volumes, historian Jole Shackelford delineates the history of the study of biological rhythms—now widely known as chronobiology—from antiquity into the twentieth century. Perhaps the most well-known biological rhythm is the circadian rhythm, tied to the cycles of day and night and often referred to as the “body clock.” But there are many other biological rhythms, and although scientists and the natural philosophers who preceded them have long known about them, only in the past thirty years have a handful of pioneering scientists begun to study such rhythms in plants and animals seriously. Tracing the intellectual and institutional development of biological rhythm studies, Shackelford offers a meaningful, evidence-based account of a field that today holds great promise for applications in agriculture, health care, and public health. Volume 1 follows early biological observations and research, chiefly on plants; volume 2 turns to animal and human rhythms and the disciplinary contexts for chronobiological investigation; and volume 3 focuses primarily on twentieth-century researchers who modeled biological clocks and sought them out, including three molecular biologists whose work in determining clock mechanisms earned them a Nobel Prize in 2017.

In three volumes, historian Jole Shackelford delineates the history of the study of biological rhythms—now widely known as chronobiology—from antiquity into the twentieth century. Perhaps the most well-known biological rhythm is the circadian rhythm, tied to the cycles of day and night and often referred to as the “body clock.” But there are many other biological rhythms, and although scientists and the natural philosophers who preceded them have long known about them, only in the past thirty years have a handful of pioneering scientists begun to study such rhythms in plants and animals seriously. Tracing the intellectual and institutional development of biological rhythm studies, Shackelford offers a meaningful, evidence-based account of a field that today holds great promise for applications in agriculture, health care, and public health. Volume 1 follows early biological observations and research, chiefly on plants; volume 2 turns to animal and human rhythms and the disciplinary contexts for chronobiological investigation; and volume 3 focuses primarily on twentieth-century researchers who modeled biological clocks and sought them out, including three molecular biologists whose work in determining clock mechanisms earned them a Nobel Prize in 2017.

In three volumes, historian Jole Shackelford delineates the history of the study of biological rhythms—now widely known as chronobiology—from antiquity into the twentieth century. Perhaps the most well-known biological rhythm is the circadian rhythm, tied to the cycles of day and night and often referred to as the “body clock.” But there are many other biological rhythms, and although scientists and the natural philosophers who preceded them have long known about them, only in the past thirty years have a handful of pioneering scientists begun to study such rhythms in plants and animals seriously. Tracing the intellectual and institutional development of biological rhythm studies, Shackelford offers a meaningful, evidence-based account of a field that today holds great promise for applications in agriculture, health care, and public health. Volume 1 follows early biological observations and research, chiefly on plants; volume 2 turns to animal and human rhythms and the disciplinary contexts for chronobiological investigation; and volume 3 focuses primarily on twentieth-century researchers who modeled biological clocks and sought them out, including three molecular biologists whose work in determining clock mechanisms earned them a Nobel Prize in 2017.