How to make your body clock work for you

Introduction

• Introduction to "ZOE Science and Nutrition"

• Importance of circadian rhythms in health and well-being

• Interview with Professor Russell Foster, an expert in circadian rhythms

Quick fire questions

• Questions from listeners about circadian rhythms and health

• Importance of circadian rhythms for health and the impact of medication timing

• Exposure to light from digital devices in the evening is not harmful

• Ways to improve sleep without drugs

• Ideal sleep schedule for teenagers and the truth about night owls

The myth of unison circadian rhythms

• Humans have varying chronotypes that determine their sleep habits

• Chronotypes depend on age, genetics, and exposure to light

• People with different chronotypes have distinct temporal structures

Importance of circadian rhythms in physiology and behavior

• Circadian rhythms influence every aspect of our health and behavior

• They optimize our biology to achieve the right substances at the right times

• The temporal structure of circadian rhythms allows us to optimize and regulate our physiology and behavior

The discovery of circadian rhythms

• The first description of a circadian rhythm was in plants in 1729

• A French astronomer observed a rhythmic opening and closing of leaves under constant darkness

• This discovery led to the hypothesis of an internal mechanism for circadian rhythms

Master clock in the brain

• The master clock for circadian rhythms is located in the hypothalamus of the brain

The Circadian Rhythm

• The circadian rhythm is abbreviated as SCN.

• The rhythm comprises about 50,000 cells and is mainly responsible for producing 24-hour oscillations in electrical activity.

• When people started researching the circadian rhythm, it was assumed that it was generated by cell-cell interactions.

• However, after isolating individual SCN neurons, scientists realized that they could tick away on their own in terms of electrical activity.

The Master Clock

• The master clock lies deep inside the brain and ticks like a little clock.

• A bunch of genes that are turned on make their proteins, forming a complex, which then enters the nucleus and turns their genes off.

• The proteins are then degraded, and the feedback loop starts again.

• The SCN was initially believed to be the only cells with this capacity. However, other types of cells also have a clock.

The Orchestra Analogy

• The master clock is similar to a conductor of an orchestra.

• It produces a rhythmic, temporal signal from which the body takes its reference queue.

• The brain's master clock coordinates the rhythmic behaviour of billions of individual cellular clocks throughout the organ systems of the body.

Why We Need Our Body Clocks

• Almost all life, including some types of bacteria, have evolved a clock which anticipates predictable changes in the environment.

• Our body clock allows us to gear up physiology and behaviour in advance of the changes.

• The different states of wake and sleep are very different, and so is our ability to process food and cognitive abilities.

The impact of our body clocks on cognitive abilities

• Processing information is impaired around 4-5 am before the body clock has started to wake a person up.

• Driving a car at this time is worse than driving under the influence of alcohol.

• Lack of sleep makes the impairment by the body clock even worse.

How the body clock synchronizes with the external world

• The master clock regulates the billions of cellular clocks in the body.

• The light-dark cycle is the most important signal for the body's internal molecular clockwork.

• Receptors in the eye detect light for the internal clock, but they are different from the rods and cones that give us our sense of space.

• The photosensitive retinal ganglion cell is the extra receptor within the eye that is directly light-sensitive and projects to the master clock within the brain.

The discovery of the third photoreceptor

• The third photoreceptor within the eye is the photosensitive retinal ganglion cell, which accounts for one out of every hundred cells.

• It was discovered in 1991 and took almost a decade to convince colleagues about the findings.

Discovery of photosensitive retinal ganglion cell

• 1999 back-to-back science papers convinced the world of the existence of a photosensitive retinal ganglion cell.

• Detected in mice, rats, and monkeys.

• Eye was the best understood part of the central nervous system, making the discovery surprising.

• An entire class of light sensors was missed for 150 years.

The Body Clock and Sleep

• The central question about the body clock is what signals from the master clock coordinate the rest of the body.

• The sympathetic nervous system regulates the activity of organs and cells.

• Neural connections through the projections of the sympathetic nervous system are essential in rhythmically changing metabolism.

• The nervous connections to key organs such as the liver regulate the rhythmic changes in the liver.

• We don't fully understand the humeral chemical messengers produced by the master clock that are regulating various tissues.

• When our circadian rhythms are not synchronized, it affects our emotional responses, cognitive responses, physiology and health.

• A comparison is made between day shift and night shift workers.

Circadian Rhythm and Jet lag

• When you travel through different time zones, it can take a day to fully synchronize to the new light-dark cycle.

• Night shift workers cannot fully adapt to the demands of working at night.

• The brightness of an environment can dictate the adapted circadian rhythm.

• Night shift workers and day shift workers are locked onto the same light dark cycle.

• Exposure to brighter light in the workplace can eventually adapt individuals to the night shift.

Emotional Responses and Our Body Clock

• Our emotional responses, cognitive responses, and physiology and health are profoundly affected by not doing the right thing at the right time.

Circadian Rhythm Disruption and Sleep Loss

• Fluctuations in mood, irritability, and loss of empathy are possible as we fail to pick up social signals from others when we are not synchronized.

• Risk-taking and impulsivity may lead us to do stupid things when we are not synchronized.

• The brain forgets positive experiences and remembers negative ones combined with sleep loss, so circadian rhythm disruption and sleep loss cause negative rather than positive memories to guide an individual's decisions.

• Excessive caffeine consumption and the subsequent high amounts of alcohol are toiled with to reverse its effects.

• Failures of multitasking, concentration, communication, and decision making all fall apart when experiencing disruptions in circadian rhythm.

Deprivation and circadian misalignment

• Shift work has a deep impact on individuals' lives, leading to deprivation and circadian misalignment

• Experiencing these for long periods can be detrimental to both physical and mental health

Ways to mitigate negative effects of shift work

• Provide vigilance devices that map head nods or eye rolls that can alert when a person is likely to fall asleep while driving

  • Such devices are being used in high-end German vehicles

• Increase the amount of light in the workplace, as increased light leads to increased alertness and less likelihood to fall asleep

• High-frequency health checks can detect potential risk for early risk cancers, obesity, and diabetes, among others

• Provide protein-rich easy-to-digest snacks in the workplace to avoid predispositions to metabolic abnormalities

• Provide education to people so that they understand the consequences of shift work on themselves and their partners since this condition can lead to a higher divorce rate, especially among night shift workers

• Try to minimize the number of people who have to work at night

Circadian rhythm and vaccination

• Frontline workers such as police officers, ambulance crews, doctors and nurses are at risk and need to be vaccinated

• A study conducted during the COVID-19 pandemic showed that vaccination is less effective if the circadian rhythm is disrupted before or after the vaccination

  • This may be due to increased levels of stress hormones that suppress the immune system

• To maximize vaccination effectiveness, frontline workers should have a period of rest and relaxation before receiving the vaccine

Impact of disrupted circadian rhythm

• Disrupting the circadian rhythm can have negative effects on the immune system and overall health

• This can increase the risk of infectious diseases and other illnesses like cancer

Importance of stable sleep-wake timing

• Stable sleep-wake timing can have long-term positive effects on health outcomes, particularly in cancer patients

  • Two-year survival rates were 70% for stable sleep-wake timing compared to 40% for disrupted sleep-wake timing

• Building stable sleep-wake timing into health programs can have significant benefits

Changes to circadian rhythm during menopause

• Changes during menopause are primarily related to changes in estrogen and progesterone hormones

• Estrogen is associated with increased sleep while progesterone promotes relaxation

• Before menstrual bleeding, when estrogen and progesterone levels are low, anxiety, depression, and irritability can increase

• The circadian system is involved in the release and regulation of hormones related to reproduction, including menstrual cycles and morning testosterone production in males

Sleep hygiene and menopause

• Good sleep hygiene suggestions:

  • Can improve sleep quality during menopause and perimenopause.

  • Has been shown to be more effective than hormone replacement therapy (HRT) in improving sleep in some women.

• There is no magic bullet for sleep troubles during menopause and perimenopause.

Circadian rhythm for gut health and metabolism

• Our circadian rhythm modulates metabolism:

  • Our ability to clear glucose is more efficient during the first half of the day, and tails off towards evening.

  • Loading calories at breakfast and lunchtime, as opposed to lunchtime and evening, promotes weight loss more effectively.

  • Our eating habits have recently changed due to the aristocracy eating later and modern work schedules.

• Eating later in the evening is detrimental to our health:

  • Studies show that having a large meal in the evening is the worst possible thing for our bodies.

  • Natural eating rhythms of working people follow the natural light-dark cycle.

• Personalized effects and further studies needed:

  • Studies are mostly done with young, healthy, male university students as volunteers, so the data sampling may not be appropriate for all groups.

Disrupting circadian rhythm due to children waking up in the night

• Small children wake up frequently in the night to feed on breast milk.

• This frequent feeding period lasts only a few weeks or months.

• Some young children seek comfort and physical contact at night even if they don't need food.

  • Developing a robust sleep weight structure, such as keeping the bedroom dark and at the right temperature, can be helpful.

  • There isn't much research on the effect of this disruption on long-term health.

• It is important for both parent and child to have structured sleep behavior.

  • Being available to your child always is not necessarily a good thing.

ZOE - About the Company and Its Goals

• ZOE's goal is to improve the health of millions through the right food to manage weight.

• It begins with an at-home test and compares the results with the world's largest nutrition science study.

• To learn more about ZOE, you can head to joinzoe.com.

• Listeners can also avail of 10% off their personalized nutrition program by entering "podcast."

Host Introduction

• Host Jonathan Wolfe greets the listeners.

Credits and Sign Off

• ZOE Science and Nutrition is produced by Fascinate Productions with support from Sharon Feder Yela and Alex Jones.

• The podcast ends with a quick goodbye from the team.