Why We Sleep Lecture Notes

This document presents key information and research on sleep and dreaming, spanning various biological, evolutionary, and social aspects. Divided into sections, the text explains the critical need for sleep, detailing sleep benefits for the brain and body, addressing sleep disorders, and examining the consequences of sleep deprivation. Additional insights are given into the stages and function of dreams, societal impacts with medicine and education, as well tips for healthier sleep habits.

Two-thirds of adults in developed nations do not get the recommended eight hours of sleep.

According to studies, what proportion of adults in developed nations fail to get the recommended amount of sleep?

Routinely sleeping less than six or seven hours a night demolishes your immune system and increases your risk of cancer.

How does insufficient sleep affect your immune system and what is the key lifestyle factor determining whether or not you will develop Alzheimer's disease?

It can profoundly disrupt blood sugar levels, potentially leading to a pre-diabetic classification.

How does inadequate sleep affect blood sugar levels?

It can increase the likelihood of blocked and brittle coronary arteries, leading to cardiovascular disease, stroke, and heart failure.

What are the cardiovascular consequences of short sleeping?

It contributes to major psychiatric conditions, including depression, anxiety, and suicidality.

What are the psychiatric impacts of sleep disruption?

Too little sleep increases hunger and suppresses feelings of food satisfaction, leading to weight gain.

How does sleep deficiency affect appetite and weight?

The shorter your sleep, the shorter your lifespan.

What is the overall impact of sleep duration on lifespan?

Human beings are the only species that will deliberately deprive themselves of sleep without legitimate gain.

What makes human beings unique in terms of sleep deprivation?

On at least two counts: a rare genetic disorder causing progressive insomnia and drowsy driving.

Can a lack of sleep kill you outright?

A sleep loss epidemic has been declared throughout industrialized nations by the World Health Organization (WHO).

What declaration has the World Health Organization (WHO) made regarding sleep loss?

To start prescribing sleep.

What are scientists lobbying doctors to start doing?

Countries where sleep time has declined most dramatically, such as the US, the UK, Japan, and South Korea.

What countries have scientists started lobbying doctors to prescribe sleep?

Doctors and scientists could not give a consistent or complete answer as to why we sleep.

Until very recently, what consistent and complete answers could doctors and scientists give regarding sleep?

You cannot gather food, socialize, find a mate and reproduce, or nurture or protect your offspring, and it leaves you vulnerable to predation.

From an evolutionary perspective, what challenges does sleep present?

Sleep dispenses a multitude of health-ensuring benefits, yours to pick up in repeat prescription every twenty-four hours.

How does sleep dispense health-ensuring benefits?

Our ability to learn, memorize, and make logical decisions and choices, as well as recalibrating our emotional brain circuits.

What functions does sleep enrich within the brain?

A consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity.

What benefits does dreaming provide?

Restocking the armory of our immune system, helping fight malignancy, preventing infection, and warding off all manner of sickness. Sleep reforms the body’s metabolic state by fine-tuning the balance of insulin and circulating glucose.

How does sleep benefit the body?

A balanced diet and exercise.

Besides sleep, what aspects are part of an important health trinity?

Twenty-plus-year research career that began when I was a professor of psychiatry at Harvard Medical School and continues now that I am a professor of neuroscience and psychology at the University of California, Berkeley.

What is the author's span of work?

There was a unique and specific electrical brain signature that could forecast which dementia subtype each individual was progressing toward.

During the author's PhD, what hypothesis was examined?

Part 1 demystifies this beguiling thing called sleep; Part 2 details the good, the bad, and the deathly of sleep and sleep loss; Part 3 offers safe passage from sleep to the fantastical world of dreams scientifically explained; Part 4 seats us first at the bedside, explaining numerous sleep disorders, including insomnia.

What are the four main parts to this book?

Two main factors: A signal beamed out from your internal twenty-four-hour clock located deep within your brain and a chemical substance that builds up in your brain and creates a “sleep pressure.”

What determines when you want to sleep and when you want to be awake?

Also known as your circadian rhythm, the powerful sculpting force of your twenty-four-hour rhythm.

What two names does your twenty-four-hour rhythm go by?

It was in 1729 when French geophysicist Jean-Jacques d’Ortous de Mairan discovered the very first evidence that plants generate their own internal time.

When and who discovered the very first evidence that plants generate their own internal time?

1938, Professor Nathaniel Kleitman at the University of Chicago, accompanied by his research assistant Bruce Richardson.

In what time and who were to perform an even more radical scientific study of endogenous circadian rhythm?

Average duration of a human adult’s endogenous circadian clock runs around twenty-four hours and fifteen minutes in length.

What is the average duration of a human adult’s endogenous circadian clock?

Sunlight.

What is the most reliable environmental signal that the brain uses to reset biological clocks?

Any signal that the brain uses for the purpose of clock resetting.

What is a zeitgeber?

The suprachiasmatic nucleus.

What is the twenty-four-hour biological clock sitting in the middle of your brain is called?

The biological circadian rhythm coordinates a drop in core body temperature as you near typical bedtime, reaching its nadir, or low point, about two hours after sleep onset.

How does biological circadian rhythm coordinate with core body temperature?

Unavoidable DNA hardwiring.

What hardwiring bounds night owls to a delayed schedule?

Melatonin.

What communicates the repeating signal of night and day to your brain and body?

At this moment, we have been served a writ of nightime, and with it, a biological command for the timing of sleep onset.

What are we served when melatonin starts rising?

Helps regulate the timing of when sleep occurs by systemically signaling darkness throughout the organism.

What role does melatonin play in sleep?

Melatonin simply provides the official instruction to commence the event of sleep, but does not participate in the sleep race itself.

In correlation with sleep, how does melatonin provide official instruction to commence sleep?

For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about one hour.

How fast can your suprachiasmatic nucleus readjust and get settled into a new zone?

Caffeine.

What can affect the sleep signal of adenosine?

It’s the equivalent of sticking your fingers in your ears to shut out a sound.

Of what is caffeine's blocking and effectively inactivating the receptors the equivalent?

Genetics.

What strongly attributes to some people's ability/inability to break down caffeine?

The sleepiness chemical it blocks (adenosine) nevertheless continues to build up.

While caffeine is in your system, what chemical it blocks continues to build up?

The twenty-four-hour circadian rhythm of the suprachiasmatic nucleus and the sleep-pressure signal of adenosine.

In actuality, what governing forces that regulate your sleep are independent which each other?

Answer two simple questions: First, after waking up in the morning, could you fall back asleep at ten or eleven a.m.? Second, can you function optimally without caffeine before noon?

What simple test can help determine if you are getting enough sleep?