Biological Rhythms & Sleep (Exam 4)

What are biological rhythms?

Regular fluctuations in living processes

What is a circadian rhythm?

A rhythm that occurs about every 24 hours

Example of a circadian rhythm?

Sleep-wake cycle

What is an ultradian rhythm?

A rhythm that occurs more than once per day

Example of an ultradian rhythm?

Sleep cycle stages

What is an infradian rhythm?

A rhythm that occurs less than once per day

Example of an infradian rhythm?

Menstrual cycle

What does endogenous mean?

Generated from within the body

What happens to rhythms without environmental cues?

They free-run

What is the master biological clock?

Suprachiasmatic nucleus (SCN)

Where is the SCN located?

Hypothalamus above the optic chiasm

What is a zeitgeber?

An external cue used to tell time

What is the main zeitgeber?

Light

What pathway carries light information to the SCN?

Retinohypothalamic pathway

What cells detect light for circadian rhythms?

Retinal ganglion cells (RGCs)

What gland releases melatonin?

Pineal gland

What effect does light have on melatonin?

Light suppresses melatonin

What effect does darkness have on melatonin?

Increases melatonin production

What happens when the SCN is damaged?

Circadian rhythms disappear

What happened after a hamster received an SCN transplant from a 20-hour donor?

Developed a 20-hour rhythm

What do clock genes regulate?

Circadian rhythms

What are the main clock genes discussed?

Clock, Cycle, Per, and Cry

What causes some people to be morning larks or night owls?

Different clock gene variants

What happens to sleep patterns during puberty?

People tend to go to sleep and wake up later

Benefits of later school start times?

Better grades, less depression, fewer car crashes

How much REM sleep do infants get?

About 50%

What happens to Stage 3 sleep as people age?

It decreases dramatically

What happens to Stage 3 sleep by age 90?

It may disappear

What records brain activity during sleep?

EEG

What are the two major types of sleep?

REM and Non-REM sleep

What brain waves occur during alert wakefulness?

Beta waves

What do beta waves indicate?

Awake and alert state

What brain waves occur when relaxed with eyes closed?

Alpha waves

What is Stage 1 sleep characterized by?

Reduced alpha waves and vertex spikes

What are vertex spikes?

Sharp waves seen in Stage 1 sleep

What are the two hallmarks of Stage 2 sleep?

Sleep spindles and K-complexes

What are sleep spindles?

12-14 Hz bursts of activity

What are K-complexes?

Large waves that help prevent waking

What brain waves dominate Stage 3 sleep?

Delta waves

What is another name for Stage 3 sleep?

Slow Wave Sleep (SWS)

What are delta waves?

High amplitude, low frequency waves

What are the characteristics of REM sleep?

Rapid eye movements, atonia, vivid dreams

What is atonia?

Loss of muscle tone

Why is REM called paradoxical sleep?

Brain appears awake while body is paralyzed

How long is one sleep cycle?

90-110 minutes

How much of sleep is usually REM?

About 20%

How much of sleep is usually Stage 2?

About 50%

When are dreams most vivid?

REM sleep

What does the activation-synthesis hypothesis suggest?

Dreams are the brain making sense of random activity

What are nightmares?

Frightening dreams during REM sleep

What are night terrors?

Sudden fearful awakenings from Stage 3 sleep

Do people usually remember night terrors?

No

How does sleep conserve energy?

Reduces heart rate, temperature, and metabolism

What is niche adaptation?

Sleeping when it is safest for survival

How does sleep help restoration?

Repairs body and brain tissues

When is most growth hormone released?

During Slow Wave Sleep

How does sleep affect memory?

Helps memory consolidation

Which sleep stage helps perceptual learning?

REM sleep

Which sleep stage helps declarative memory?

Slow Wave Sleep

What brain area promotes Slow Wave Sleep?

Basal forebrain

What neurotransmitter does the basal forebrain release?

GABA

What brain area promotes wakefulness?

Reticular formation

What happens if the reticular formation is stimulated?

Wakefulness increases

What happens if the reticular formation is damaged?

Continuous sleep

What brain region triggers REM sleep?

Subcoeruleus in the pons

What causes REM atonia?

Inhibition of motor neurons

What brain region coordinates sleep stages?

Hypothalamus

What is narcolepsy?

Sudden sleep attacks with immediate REM

What is cataplexy?

Sudden loss of muscle tone while awake

What is insomnia?

Difficulty falling asleep or staying asleep

What is sleep-onset insomnia?

Difficulty falling asleep

What is sleep-maintenance insomnia?

Difficulty staying asleep

What is sleep apnea?

Repeated stopping of breathing during sleep

How is sleep apnea commonly treated?

CPAP

What is somnambulism?

Sleepwalking

What is sleep enuresis?

Bedwetting

What is REM Behavior Disorder?

Acting out dreams because paralysis is absent

What is SIDS?

Sudden Infant Death Syndrome

What causes sleep state misperception?

Feeling awake despite EEG showing sleep

Effects of sleep deprivation?

Irritability, poor concentration, slower reaction time

What are microsleeps?

Brief involuntary episodes of sleep

How long did Randy Gardner stay awake?

11 days

What happens during sleep recovery?

More Stage 3 sleep and intense REM sleep

Can all lost sleep be recovered?

No

Sleep Hygiene

What should you do when you feel sleepy?

Go to bed

What time should you wake up?

The same time every day

Should you nap often?

No

What should you avoid before bed?

Caffeine and screens

Why are screens bad before bed?

Blue light suppresses melatonin

What environment promotes sleep?

Quiet, dark, and cool