Prof. William Schwartz and Prof. Roelof A. Hut have published a new freely available book: On the Essential Principles and Practice of Circadian Biology: A Road Map.
This book can be viewed here: https://doi.org/10.21827/68629ef93c8d0

Abstract:
Circadian Biology is about the adaptation of life to our rotating world, to the Earth’s 24-hour rhythm of day and night. Not surprisingly, the field has attracted considerable popular and scientific interest from people seeking further study or applications. This new diversity is exciting and invigorating! But newcomers may have little or no foundational knowledge on the essential principles and practice of circadian biology, no framework upon which to incorporate their disciplinary experience and expertise. If this describes you, our intention is to provide you with a Road Map – call it a launching pad, jump start, gateway, or primer – as a first (and hopefully engaging and helpful) step to enter the field and as an entrée to its now voluminous literature.