Circadian Science
The circadian rhythm is a biological process governed by an internal timing mechanism that operates on an approximately 24-hour cycle. These rhythms influence sleep patterns, hormone release, appetite, digestion, and temperature regulation. The human circadian clock synchronizes with the natural day-night cycle, using sunlight as its primary cue, and resets each morning with exposure to sunrise. In 2017, the Nobel Prize was awarded for the discovery of the molecular mechanisms that control circadian rhythms.
Sunlight is the primary regulator of our internal clock. The eye serves as the sole pathway for light information, projecting directly to the master pacemaker located in the hypothalamus (Reference 700).
The human circadian clock synchronizes with sunlight. Our biological clock, which governs everything from gene expression to behavior, aligns with the Earth’s 24-hour rotation through environmental cues known as zeitgebers. This active alignment process is called entrainment (Reference 701).
Improving your well-being starts with restoring your circadian rhythms, the internal mechanisms that synchronize your biological processes with the natural cycle of day and night (Reference 118).
Nearly all organisms have evolved internal clocks that coordinate physiological processes, ensuring that distinct functions take place at specific times throughout the day. This adaptation allows organisms to synchronize their behavior and biology with the daily cycle of light and darkness (Reference 550).
Because our environment is shaped by the Earth's rotation, it is natural that organisms have adapted by developing circadian rhythms that regulate physiological and behavioral activities throughout the day (Reference 551)
Circadian Timeline
This timeline highlights significant dates in the evolution of circadian biophysics.
1865 – MAXWELL EXPLAINS LIGHT
Physicist and mathematician James Clerk Maxwell showed that light is an electromagnetic wave. In 1865, he wrote down the equations describing these waves, revealing that different wavelengths of light are perceived as different colors.
1893– ARTIFICIAL LIGHT GOES PUBLIC
The 1893 World’s Columbian Exposition in Chicago is widely recognized as the landmark event that introduced large-scale artificial electric lighting to the public.
1903 NOBEL PRIZE FOR UV LIGHT THERAPY
Niels Ryberg Finsen won the Nobel Prize in Medicine for pioneering the use of ultraviolet light therapy to treat lupus vulgaris, a form of skin tuberculosis.
1905 – EINSTEIN’S PHOTOELECTRIC EFFECT
In March 1905, Einstein — then still working as a patent clerk in Switzerland — published a paper explaining the photoelectric effect. He proposed a groundbreaking idea: that light can behave as a particle, later called a photon. In his theory, when light strikes a material surface, it transfers energy to the electrons in that material.
1923 –THE ONION ROOT EXPERIMENT: CELLS COMMUNICATE WITH LIGHT
In 1923, Alexander Gurwitsch’s onion root experiment became a foundation of biophoton research by suggesting that living cells emit weak ultraviolet light. Using quartz, which transmits UV light, he showed that one root could stimulate cell division in another without chemical contact—a phenomenon he called “mitogenetic radiation.”
1929 –SUNGLASSES BECOME POPULAR
Mass-produced sunglasses became popular in America in 1929, when Sam Foster introduced inexpensive celluloid shades on the Atlantic City boardwalk. Sold under the Foster Grant name at Woolworth’s, they quickly evolved from a practical beach accessory into a widespread fashion trend. Some critics argue that sunglasses contribute to health problems by reducing melanin production, decreasing melatonin, and disrupting circadian signaling.
1948 - CLAUDE SHANNON CREATES MODERN INFORMATION THEORY
Claude Shannon’s landmark 1948 paper, “The Mathematical Theory of Communication,” showed that a message’s informational value depends largely on how unusual the message was.
1959 – THE TERM “CIRCADIAN” IS NAMED
Franz Halberg coined the term “circadian,” from the Latin circa (“about”) and dies (“day”), to describe self-sustained biological oscillations.
1973 - JOHN OTT DISCOVERS LIGHT’S EFFECT ON ADHD
In 1973, Dr. John Ott studied four windowless first-grade classrooms in Sarasota, Florida, and found that replacing cool-white fluorescent lights with full-spectrum lighting and radiation shielding improved behavior and reduced hyperactivity. Students in the full-spectrum rooms were less “off-the-wall,” and one hyperactive boy showed marked gains in focus and learning within 90 days.
1977 – ROBERT O. BECKER ON 60 MINUTES
Dr. Robert O. Becker appeared on 60 Minutes to warn that electromagnetic fields from power lines and other electrical infrastructure could pose serious health risks. His research in the 1960s and 1970s made him a leading public critic of overhead power cables and high-voltage transmission lines.
1986 – THE ORIGINS OF CIRCADIAN MEAL TIMING
French physician Alain Delabos introduced the idea that eating patterns should align with natural circadian rhythms, favoring larger meals earlier in the day and smaller, lighter meals in the evening.
1983 – THE OVERCOMING JETLAG GUIDE
Charles Ehert’s guide Overcoming Jetlag was published as a practical resource on managing light exposure, diet, and meal timing to help travelers adjust more quickly to new time zones.
1905 – EINSTEIN FORMULATES E=MC2
In Einstein’s famous equation, E stands for energy, M stands for mass, and C stands for the speed of light. Because mass and light are linked through this equation, biology can read it in reverse to show how light can be turned into energy and matter. This means that when light is slowed down, it gains structure and becomes mass, matter, or form. In this framework, food is light slowed down, photons are light without mass, and matter is light that has become encumbered by mass. Thus, E = MC² describes how light sculpts matter and how the optical density can slow time or slow entropy.
1994 – LEPTIN IS DISCOVERED
Leptin, the hormone produced by fat cells that regulates food intake and energy expenditure, was discovered in 1994 at Rockefeller University.
1998 - MELANOPSIN IS DISCOVERED
Melanopsin is a light-sensitive protein found in the brain, eyes, skin, and throughout the body. It responds to blue light, triggering wakefulness and alertness.
2000 – THE CIRCADIAN PRESCRIPTION
Sydney MacDonald Baker’s book Circadian Prescription was published as a health guide outlining a ten-point diet and lifestyle program designed to align daily routines with the body’s internal biological clock.
2007 – JACK KRUSE’S KNEE INJURY SPURS A NEW DIRECTION
In 2007, Nashville neurosurgeon Dr. Jack Kruse tore his meniscus while giving a talk on surgical equipment, an event he later described as the start of his exploration into circadian biology, the leptin-melanocortin pathway, and the biophysics of sunlight.
2012 – DR. KRUSE BANNED TED TALK
Dr. Jack Kruse delivered his banned TED Talk in Nashville, centered on light, water, and magnetism as the “three-legged stool” of human health. The talk was not officially released through TED’s mainstream channels because of its controversial nature.
2012 – DR. KRUSE REMOVED FROM LOW-CARB CRUISE
On May 6, 2012, Dr. Jack Kruse, who was scheduled to speak on Jimmy Moore’s 5th Annual Low-Carb Cruise, was removed from the ship after a fake tweet from an impostor account falsely claimed he was carrying a vial of Legionnaires’ disease.
2013: DR. JACK KRUSE PUBLISHES EPI-PALEO RX
Dr. Jack Kruse’s book Epi-Paleo Rx: The Prescription for Disease Reversal and Optimal Health was published in March 2013.
2017: THE NOBEL PRIZE FOR CIRCADIAN BIOLOGY
The Nobel Prize in Physiology or Medicine was awarded to American researchers Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for discovering the molecular mechanisms that govern circadian rhythms, revealing how biological clocks synchronize with Earth’s 24-hour day–night cycle.
2023 – RICK RUBIN PODCAST WITH DR. KRUSE & ANDREW HUBERMAN
The release of Rick Rubin’s Tetragrammaton podcast featuring Dr. Jack Kruse and Andrew Huberman brought Dr. Kruse’s circadian biology research to a broader mainstream audience.
2026 – DR. KRUSE DISCUSSES MAGNETIC DECLINATION
On April 9, 2026, Dr. Jack Kruse discussed magnetic declination in an interview; later coverage by a news program sensationalized his remarks, prompting clarification in subsequent interviews.