🗓️Unit 4
Sleep

PSYC 181 – Intro to Psych

Emma Marshall – Instructor

University of Nebraska-Lincoln

July 22, 2024

What you will learn

Learning Objectives

• Define consciousness
• Understand sleep and its stages
• Describe theories of why we sleep and dream
• Identify major sleep disorders

What is consciousness?

Consciousness: awareness of internal and external stimuli such as feelings of hunger and pain or detection of light

Wakefulness: high levels of sensory awareness, thought, and behavior

Biological Rhythms

A biological rhythm is an internal cycle of biological activity including: Fluctuation of body temperature. An individuals menstrual cycle. Levels of alertness.

Circadian Rhythms

Occurs over approximately 24 hours

Generated by the suprachiasmatic nucleus (SCN). The sleep-wake cycle, one of our main circadian rhythms is linked to our environments natural light-dark cycle.

This chart illustrates the circadian change in body temperature over 28 hours in a group of eight young men. Body temperature rises throughout the waking day, peaking in the afternoon, and falls during sleep with the lowest point occurring during the very early morning hours.

The Suprachiasmatic Nucleus (SCN)

serves as the brain’s clock mechanism

The suprachiasmatic nucleus (SCN), located in the hypothalamus, serves as the brain’s clock mechanism. The clock sets itself with light information received through projections from the retina, allowing it to synchronize with the outside world.

Melatonin and Sleep Regulation

Our sleep—wake cycle is also regulated by other factors such as the hormone melatonin. Melatonin release is stimulated by darkness, making us sleepy, and inhibited by daylight. Melatonin is released by the pineal gland.

Sleep regulation – the brain’s control of switching between sleep and wakefulness as well as coordinating this cycle with the outside world. Each person has an individual circadian pattern of activity known as a person’s chronotype.

Disruptions of Normal Sleep

Certain circumstances can throw off our circadian rhythms

Jet lag: mismatch between our internal circadian cycles and our environment

Rotating shift work: Becomes difficult for a normal circadian rhythm to be maintained.

Jet lag – Symptoms resulting from the mismatch between our internal circadian cycles and our environment. Fatigue, sluggishness, irritability and insomnia. Rotating shift work – A work schedule that changes from early to late on a daily/weekly basis. Becomes difficult for a normal circadian rhythm to be maintained. Can result in persistent feelings of exhaustion and agitation, sleeping problems and can lead to signs of depression and anxiety. Bright light can be used to realign our biological clocks with the external environment.

Bright light

Bright light can be used to realign our biological clocks with the external environment

Sleep Needs at Different Ages

Age	Recommended	May be appropriate	Not recommended
0–3 months	14–17 hours	11–13 hours 18–19 hours	Fewer than 11 hours More than 19 hours
4–11 months	12–15 hours	10–11 hours 16–18 hours	Fewer than 10 hours More than 18 hours
1–2 years	11–14 hours	9–10 hours 15–16 hours	Fewer than 9 hours More than 16 hours
3–5 years	10–13 hours	8–9 hours 14 hours	Fewer than 8 hours More than 14 hours
6–13 years	9–11 hours	7–8 hours 12 hours	Fewer than 7 hours More than 12 hours
14–17 years	8–10 hours	7 hours 11 hours	Fewer than 7 hours More than 11 hours
18–25 years	7–9 hours	6 hours 10–11 hours	Fewer than 6 hours More than 11 hours
26–64 years	7–9 hours	6 hours 10 hours	Fewer than 6 hours More than 10 hours
≥65 years	7–8 hours	5–6 hours 9 hours	Fewer than 5 hours More than 9 hours

Individual Differences

Morning vs. Night person

Teaching Suggestion: Personality and Sleep

Main Focus: Incorporate into your lecture some of the research on personality and sleep. Subject: Personality and Sleep Description: Incorporate into your lecture some of the research on personality and sleep. This material can include the personality correlates with morningness and eveningness (Randler, 2008), personality and susceptibility to sleep deprivation (Killgore, Richards, Killgore, Kamimori, & Balkin, 2007), and whether personality is a factor in cognitive performance after sleep deprivation (Taylor & McFatter, 2003). Time: 10 minutes

References: Killgore, W. D., Richards, J. M., Killgore, D. B., Kamimori, G. H., & Balkin, T. J. (2007, December 16). The trait of Introversion–Extraversion predicts vulnerability to sleep deprivation. Journal of Sleep Research, 16(4), 354–363.

Randler, C. (2008, July). Morningness–eveningness, sleep–wake variables and Big Five personality factors. Personality and Individual Differences, 45(2), 191–196.

Taylor, D. J., & McFatter, R. M. (2003). Cognitive performance after sleep deprivation: Does personality make a difference? Personality and Individual Differences, 33, 1179–1193.

Sleep deprivation

Sleep debt: result of insufficient sleep on a chronic basis.

Sleep rebound: a sleep-deprived individual will fall asleep quicker

This figure illustrates some of the negative consequences of sleep deprivation. While cognitive deficits may be the most obvious, many body systems are negatively impacted by lack of sleep.

Sleep Debt and College Students

via GIPHY

Main Focus: Discuss a famous case of sleep deprivation. Subject: Sleep Deprivation Description: In 1965, college student Randy Gardner remained awake for 11 days, seemingly without harm to his mind or body. This famous case makes for a good lecture addition, and it can be used to segue into a longer discussion or class assignment on sleep deprivation and the importance of sleep to our normal function. Time: 5 minutes

https://www.newscientist.com/article/mg20627562-100-randy-gardner-the-17-year-old-schoolboy-who-didnt-sleep-for-11-days/

What is sleep?

Sleep is associated with the secretion and regulation of many hormones including:

• Melatonin
• Follicle stimulating hormone
• Luteinizing hormone
• Growth hormone

Sleep is a state marked by relatively low physical activity and a reduced sense of awareness. Sleep-wake cycles seem to be controlled by multiple brain areas including the thalamus and hypothalamus (slow-wave sleep) and the pons (REM sleep).

Brain Areas involved in sleep

The pineal and pituitary glands secrete a number of hormones during sleep

Why Do We Sleep?

Evolutionary Theory

Cognitive function

• Important for memory formation and consolidation Focuses on sleeps importance for cognitive function and memory formation. Research shows that sleep deprivation results in disruptions in cognition and memory deficits. These impairments become more severe as the amount of sleep deprivation increases. Slow-wave sleep appears to be essential for effective memory formation.

Restoration theory

Allows body to rest and repair

Maintaining a healthy weight, lowering stress levels, improving mood, increased motor coordination as well as many benefits related to cognition and memory formation.

Waste Management System

Q. I’ve heard that toxins are flushed out of the brain during sleep. Is that true?

A. One of the most interesting discoveries in the past decade is that the brain has a “waste management system.” Like people, in order to have the energy to do their work, brain cells need to eat (to absorb, primarily, sugar and oxygen). And, as in people, meals lead to wastes that need to be disposed of. The waste management system (called the glymphatic system) is a series of tubes that carry fresh fluid into the brain, mix the fresh fluid with the waste-filled fluid that surrounds the brain cells, and then flush the mix out of the brain and into the blood. This occurs primarily during deep sleep.

There is some evidence that an under-functioning waste management system may play a role in the neurodegeneration that follows traumatic brain injury (as experienced by some football players, for example). It may even play a role in other brain disorders, including Alzheimer’s disease. Since chronic sleep deprivation increases the risk for various brain diseases, it is plausible that it does so by reducing the function of the waste management system.

Why do we sleep? We know it helps to rest the body and to consolidate memories and learning. Perhaps we also need to sleep to flush wastes from our brain.

Stages of Sleep

Brain Waves During Sleep

Dramatically changes in activity across stages of sleep can be visualized using EEG

• Alpha relatively low frequency, relatively high amplitude, synchronized
• Theta: low frequency, low amplitude
• Delta low frequency, high amplitude, desynchronized

• Stage 1: Transitional phase, alpha waves
• Stage 2: Deep relaxation, theta waves, sleep spindles, and K-complexes
• Stages 3 & 4: Slow-wave sleep, delta waves
• REM (Rapid Eye Movement): Dreams, paralysis of voluntary muscles

Stage 1

Alpha waves

• Transitional phase between wakefulness and sleep
• Respiration and heartbeat slows
• Muscle tension and body temperature decrease

Stage 2

Theta waves

• Body enters deep relaxation
• Appearance of sleep spindles and K-complexes

Sleep Spindles & K-complexes

• Sleep spindles: rapid burst of high frequency brainwaves
• K-complexes: very high amplitude pattern of brain activity

Stages 3 and 4

Delta waves

• Known as slow-wave sleep
  
• Respiration and heart rate slow down further

Rapid Eye Movement (REM)

Brain waves are similar to those seen during wakefulness

• Paralysis of voluntary muscles
• Dreams

Hypnogram of sleep stages

Diagram of the stages of sleep as they occur during a period of sleep

A hypnogram is a diagram of the stages of sleep as they occur during a period of sleep. This hypnogram illustrates how an individual moves through the various stages of sleep.

Dreams

Unclear why we dream!

Dreams are the product of an altered state of consciousness Little is known about why we dream the way we do Everyone dreams – even if they do not remember Can be vivid and realistic Often do not know dreaming until wake up

Dream Theories

Many ideas about how to interpret dreams

• Sigmund Freud: Saw dreams as a way to gain access to the unconscious.
  • Manifest content: the actual dream content
  • Latent content: the hidden meaning

• Carl Jung: Believed that dreams allowed us to tap into the collective unconscious.
  • Collective unconscious: repository of information shared by all people across cultures
  • Symbols reflect universal archetypes

Activation-Synthesis Theory

Some support in neuropsychology

• Brain tries to make sense of random activity during sleep
• Emotion centers (limbic system) active
  • intense emotions
• Frontal cortices are not active
  • Uncritically accept illogical events

REM vs. Non-REM Dreams

Sleep Disorders

• Insomnia: Difficulty falling or staying asleep
• Parasomnias: Unwanted behaviors during sleep (e.g., sleepwalking, night terrors)
• Sleep apnea: Breathing stops during sleep
• Narcolepsy: Irresistible urge to fall asleep during waking hours

Insomnia (most common)

Defined by difficulty falling or staying asleep for at least 3 nights a week for at least one month’s time.

Contributing factors:

• Age
• Drug use
• Exercise
• Mental status
• Bedtime routines

Insomnia (treatment)

• Stress management
• Changes in problematic behaviors that could contribute to insomnia
• Cognitive-behavioral therapy

Parasomnia

Unwanted motor behavior/experiences throughout the sleep cycle

Sleep walking: Usually occurs during slow-wave sleep.

REM sleep behavior disorder: Occurs when the muscle paralysis associated with REM sleep does not occur.

Includes high levels of physical activity during REM sleep. Often treated with Clonazepam (an anti-anxiety medication).

Restless leg syndrome: Involves uncomfortable sensations in the legs when trying to fall asleep that are relieved by moving the legs. Can be treated with a variety of medications.

Night terrors: Sleeper experiences a sense of panic and may scream or attempt to escape. Occur during NREM sleep.

Sleep Apnea

Occurs when individuals stop breathing during their sleep, usually for 10-20 seconds or longer.

• Obstructive: airway becomes blocked and air is prevented from entering the lungs.

• Central: CNS fails to initiate breaths.

Treatment can include a continuous positive airway pressure (CPAP) device which pumps air into the person’s airways

Narcolepsy

Involves an irresistible urge to fall asleep during waking hours

• Cataplexy: loss of muscle tone while awake or in some cases complete paralysis of the voluntary muscles.

• Hypnagogic hallucinations: vivid, dream-like hallucinations.

• Treatment: psychomotor stimulant drugs.

Sleep & Dream Log