Body Rhythms & Sleep

What is Consciousness?• Consciousness – Your immediate awareness of thoughts,

sensations, memories, and the world around you. Experience of this tends to blend together.

• William James – described consciousness as a "stream" or "river" that is always changing but unified and unbroken.

• Consciousness first studied through introspection (verbal self-reports) and later rejected in favor of studying only observable overt behavior.

• 1950's brought a new desire to study consciousness for two reasons.

1. Complete understanding of behavior had to consider the role of conscious mental processes.

2. Psychologists had created more objective ways to study consciousness.

Body Rhythms•Natural variations we experience daily in our consciousness as a part of our sleep-wake cycle. •Most people experience at least two peaks in mental alertness:

1. morning around 9:00 or 10:00 and 2. 8:00 or 9:00 PM. –Slumps in your mental alertness occur at about 3:00 PM and 3:00 AM.

Biological Rhythms• Periodic physiological fluctuations

• Can affect physiological functioning

• Fall into three main categories

– Circadian Rhythms

– Ultradian Rhythms

– Infradian Rhythms

Circadian Rhythms• Any rhythmic change that occurs approximately

once in a 24-hour cycle • body temperature

• cortisol secretion

• sleep and wakefulness

• In the absence of time cues, the cycle period will become somewhat longer than 24 hours

• Many of your processes like blood pressure, hormones, pain sensitivity along with sleep and wake cycles vary over the day

Sleep and Circadian Rhythms

• Play “Sleep and Circadian Rhythms” (6:09) Module #13 from The Brain: Teaching Modules (2nd edition).

• Intro to Circadian Rhythms & Cave Experiment

The Body’s Clock• Suprachiasmatic

nucleus (SCN)—cluster of neurons in the hypothalamus that governs the timing of circadian rhythms

• Melatonin—hormone of the pineal gland that produces sleepiness

The Body’s Clock: How it works• Special photoreceptors in the retina regulate the

effects of light on the body’s circadian rhythms • In response to morning light, signals from these

special photoreceptors are relayed via the optic nerve to the suprachiasmatic nucleus.

• In turn, the suprachiasmatic nucleus causes the pineal gland to reduce the production of melatonin, a hormone that causes sleepiness.

• As blood levels of melatonin decrease, mental alertness increases.

• Daily exposure to bright light, especially sunlight, helps keep the body’s circadian rhythms synchronized and operating on a 24-hour schedule.

IMPROVING SLEEP & MENTAL ALERTNESS

• Dealing with Morning Brain Fog or Sleep Inertia• Staying in bed until the last possible moment will

only intensify disorientation as you hustle to work.• Best way to treat it is to allow for more passage of

time. • Set your alarm 15 minutes earlier and make it so you

have to get up to turn it off. • Drink something with caffeine and sit near sunlight. • Read something to get your brain engaged.

How Melatonin works:• More melatonin = sleepy and reduce activity levels

(between 1-3 AM)• Less Melatonin = more alert and active. Body stops

produced melatonin shortly before sunrise and sunlight suppresses melatonin levels throughout the day

• Jet Lag – Since your body is still operating on the time you left from, your melatonin levels will be off causing a disruption in your circadian rhythms and making you mentally fatigued, depressed, irritable and have problems sleeping.

• Night workers will always have some problems due to sunlight resetting their biological clock.

Biological Rhythms

• Play “Can You Beat Jet Lag?” (6:44) Segment #15 from Scientific American Frontiers: Video Collection for Introductory Psychology (2nd edition).

• How light is used by the body to “reset” your biological clock.

Coping with the Night Shift

• Avoid frequent shift changes• Easier to lengthen your days than shorten them.

Progress morning to evening to night shifts.• If working at night use bright lights especially

early on in the shift to adjust your circadian rhythm.

• Take melatonin in the daytime to help you sleep.• Some major health issues could occur: See

NBC Nightly News Report

Ultradian Rhythms

• Biological rhythms that occur more than once each day

• Example: Cycling through the stages of sleep throughout the night

Infradian Rhythms

• Biological rhythms that occur once a month or once a season

• Example: Women’s menstrual cycle or a bear’s winter hibernation

Biorhythms vs. Circadian Rhythms

• Biorhythms – pseudoscience that says people have three natural rhythms that follow cycles. 23-day physical cycle, 28-day emotional, and 33-day intellectual functioning. These are determined by the date of your birth.

• Chronobiology – study of biological rhythms over time. Studies have not scientifically proven that biorhythms play a role in certain events (pg. 141).

A Sleep SurveyMost people will spend about 22 years of their

life sleeping. How much are you spending?

1. To the nearest quarter hour, what is your bedtime on a school night?

2. On the average, how many minutes does it take you to fall asleep after going to bed?

3. To the nearest quarter hour, how many hours of sleep do you get on an average school night?

A Sleep Survey

4. In an average night, how many times do you wake up?

5. On a scale of 1 to 10, with one being poor and 10 being wonderful, rate the quality of your sleep on a typical night.

6. On a scale of 1 to 10, with one being easy and 10 being difficult, how hard is it for you to wake up in the morning?

A Sleep Survey

7. In a typical 7-day week, how many naps do you take?

8. When are you generally most awake and alert?

-Morning -Afternoon -Evening -Night

A Sleep Survey

9. After a typical night’s sleep, how many dreams do you recall?

10. Which term most accurately describes your typical dream?

-Pleasant

-Unpleasant

-Neutral

Sleep and Sleep Deficit

Sleep Deprivation Effects• Hurts performance on simple, boring tasks more than

challenging ones• Decreases efficiency of immune system functioning• Raises the levels of stress hormone cortisol which is linked

to damage of the brain cells responsible for learning & memory

• Safety and accident issues• Contributes to hypertension, impaired concentration,

irritability, premature aging, etc.• After one night of sleep deprivation, people have episodes

of sleep lasting a few seconds called microsleeps• Lack of Sleep is a serious problem in America –

Sleepless in America NBC Report (2 min).• What are Sleep Studies Finding? (3 min NBC interview)

Sleep Deprivation(National Transportation Safety Board, 1995)

Sleep Deprivation Studies• Play “Catching Catnaps” (11:45) Segment #13 from

Scientific American Frontiers: Video Collection for Introductory Psychology (2nd edition). – Start at 1:12

• Which stages of sleep are most important?• Can a person survive on naps alone?• How does lack of sleep or “bonus” sleep affect

mood?• Watch Fatal Familial Insomnia (4 min) • What happens when you are unable to sleep…ever?

Why We Sleep•Most people need 8-8.5 hours of sleep to function but most Americans sleep 7-7.5 hours. Almost 1/3 of Americans get less than 6 hours. 74% women sleep less than 8 hours a night.

•Most teens need 9 hours and 15 minutes of sleep a night. Average teenager's biological clock doesn't prepare them to awaken until 8 or 9 AM. This can interfere with memory and learning. Students with most sleep did better on grades and exams.

•Getting less sleep than you need can cause harmful changes in metabolic and endocrine functioning. Study found after only one week of sleep restriction of 4 hours of sleep a night, subjects had glucose levels that were no longer normal.

•REM deprivation will cause subjects to have REM rebound in which they spend more time in REM sleep in an effort "catch up."

•Stage 3 & 4 NREM deprivation – people will have NREM rebound and "catch-up" by spending more time in these stages.

Functions of Sleep• Restoration theory—body wears out during the day and

sleep is necessary to put it back in shape– NREM sleep sees increases in the release of growth hormone,

testosterone, prolactin.– REM sleep plays a role in rate of brain development that occurs in

the early stages of the lifespan.

• Adaptive theory—sleep emerged in evolution to preserve energy and protect during the time of day when there is little value and considerable danger– Animals with few natural predators sleep the most while animals

with many sleep less. – Hibernation occurs during the time of year most hazardous to the

animal.

Improving the Quality of Your Sleep• Avoid going to sleep in the "forbidden zone" of wakefulness that

usually occurs between 8-10PM.• Don't drink or eat caffeine-containing drinks or foods. See table

4.7 on pg. 175 for common sources of caffeine.• Don't go to bed very hungry or full• Moderate exercise during the day helps but not just before sleep.• Raise your core body temperature with a warm bath or shower.• Develop a consistent bedtime routine.• Avoid depressant drugs which promote sleep but reduce REM

sleep.• Write down concerns and what you plan to do about them the

next day or redirect your thoughts to something relaxing to deal with stress.

Sleep Stages, REM, and Dreaming:

The Stages of Sleep

Electroencephalograph (EEG)

• A machine that amplifies and records waves of electrical activity that sweep across the brain’s surface

• Electrodes are placed on the person’s scalp to measure the waves

• Used as a means to measure the stages of sleep

Electroencephalogram (EEG)

• Electrodes placed on the scalp provide a gross record of the electrical activity of the brain• EEG recordings are a rough index of psychological states

EEG Waves of Wakefulness

• Awake, but non-attentive: large, regular alpha waves

1 second

Alpha waves

Awake, nonattentive

1 second

Beta waves

Awake, attentive• Awake and

attentive: low amplitude, fast, irregular beta waves

Onset of Sleep• Awake & alert, your brain produces small, fast

brain waves called beta waves.• As you lay down and close your eyes, your brain's

electrical activity gradually gears down generating slightly larger and slower alpha brain waves.

• During drowsy, presleep stage you may experience vivid sensory phenomena called hypnagogic hallucinations.

• Most common hallucination is that of falling which can produce a myoclonic jerk or sleep starts – involuntary muscle spasm of the whole body that jolts the person completely awake.

Stage 1 Sleep• Breathing is slowed.• Brain waves become irregular.• It is easy to wake the person, who will

insist they are not asleep.• Lasts only a few minutes. • Familiar sounds fade away but your can

regain alertness if something interrupts you.

• Some imagery is common although NOT very strange or vivid.

Stages of Sleep

Observe Stage Alpha waves

Stage 1

Stage 1

Observe Stage 1 Sleep

waves

Stage 2 Sleep• Brain wave cycle slows.

• Appearance of sleep spindles or brief bursts of brain activity and K complexes or large high-voltage spikes of brain activity that periodically occur.

• Brain activity slows considerably and breathing becomes rhythmic.

• Slight muscle twitches occur.

• Brain waves begin to slowly switch from Theta waves to slower and larger delta waves.

Stage 2

K Complex

Observe Stage 2 Sleep

waves

Stages 3 and 4 Sleep“Slow Wave Sleep”

• Increase in delta waves (large and slow waves per second) 20% = Stage 3. More than 50% = Stage 4.

• First time through stage 4 is about 30 minutes and is where one gets rejuvenated

• During the first stage 4 of sleep, heart rate, blood pressure and breathing drop to their lowest levels and it is very hard to wake up.

• Sleepwalking occurs here. • People can "wake up" during stage 4 and do a

simple task and not remember it.

Stage 3

Observe Stage 3 Sleep

waves

Stage 4

Observe Stage 4 Sleep

waves

Stages of Sleep1-4Quick Review

• Sleep stage 1: brief transition stage when first falling asleep

• Stages 2 through 4 (slow-wave sleep): successively deeper stages of sleep

• Characterized by an increasing percentage of slow, irregular, high-amplitude delta waves

• Can you tell when a person’s EEG shifts from one stage to the next? Try it yourself!

Delta waves

Sleep stage 11 second

Sleep stage 4

Sleep stage 2

Spindlers (bursts of activity)

REM Sleep

• Stages 1 - 4 considered N-REM (non-REM sleep)

• Rapid eye movement (REM Sleep) as eyes move quickly back and forth

• Most dreaming occurs in REM sleep but muscle activity is suppressed to keep you acting them out.

• If denied REM sleep and then allowed a person will experience REM Rebound and will increase their time in REM by 50%. “Catching Up” on REM sleep.

REM Sleep

Observe REM Sleep

waves

REM: Paradoxical Sleep• During REM sleep brain wave patterns are

similar to when a person is awake• Visual and motor neurons in the brain fire like

they do when you are awake.• Eyes dart back and forth and heart rate, blood

pressure and respirations fluctuate up and down.

• REM sleep is sometimes called paradoxical sleep as one’s physiology is close to that of being awake but the brainstem blocks all muscle movement

• The first REM cycle lasts for 5 to 15 minutes.

Stages of Sleep

• Upon reaching stage 4 and after about 80 to 100 minutes of total sleep time, sleep lightens, returns through stages 3 and 2

• REM sleep emerges, characterized by EEG patterns that resemble beta waves of alert wakefulness– muscles most relaxed– rapid eye movements occur– dreams occur

• Four or five sleep cycles occur in a typical night’s sleep; less time is spent in slow-wave, more is spent in REM

Typical Night’s Sleep

Stage 4/REM Changes

Sleep Changes through Life

Sleep• Play “Sleep: Brain Functions” (11:12)

Module #14 from The Brain: Teaching Modules (2nd edition).

• Review of the stages of sleep & preview of sleep disorders.

• What happens to animals that are not allowed to sleep?

• What defines normal & abnormal sleep?• Categories of Sleep Disorders