Circadian Rhythms and Sleep Stages

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the typical duration of the human circadian cycle without external light information?

Approximately 25 hours (correct)

Close to 27 hours

About 26 hours

Less than 24 hours

Which brain wave pattern is commonly associated with an awake individual under mental concentration?

Beta waves (correct)

Alpha waves

Theta waves

Delta waves

What is the average time to the first REM period after falling asleep?

30 minutes

60 minutes

120 minutes

90 minutes (correct)

What characterizes sleep architecture changes with age?

Reduced delta sleep Signup and view all the answers

During non-REM sleep, which stages are included?

Stages 1, 2, 3, and 4 Signup and view all the answers

What effect do sedative agents like alcohol and benzodiazepines have on sleep?

Reduce REM sleep and delta sleep Signup and view all the answers

How often do REM periods occur throughout the night?

Every 90 minutes Signup and view all the answers

What happens to REM sleep if a person is deprived of it one night?

They have increased REM sleep the next night Signup and view all the answers

Which management technique is recommended for insomnia?

Establishing a sleep ritual Signup and view all the answers

What is a primary management strategy for obstructive sleep apnea?

Weight loss for overweight individuals Signup and view all the answers

Which of the following is NOT a recommended intervention for managing narcolepsy?

Weight loss techniques Signup and view all the answers

What role does relaxation play in the management of insomnia?

It can be used as a technique to aid sleep hygiene Signup and view all the answers

What is the utility of CPAP therapy in sleep disorders?

It is a treatment for breathing-related sleep disorders Signup and view all the answers

Which EEG pattern is associated with the awake state?

Beta and Alpha waves Signup and view all the answers

What percentage of sleep time is typically spent in Stage 2 of sleep?

45% Signup and view all the answers

Which stage of sleep is characterized by the occurrence of nightmares and sleepwalking?

Stages 3 and 4 Signup and view all the answers

What is a common symptom experienced during narcolepsy associated with emotional triggers?

Cataplexy Signup and view all the answers

How is REM sleep different from other stages of sleep?

It involves dreaming and increased physiological activity Signup and view all the answers

What percentage of REM sleep typically decreases with age?

25% Signup and view all the answers

What phenomenon occurs just as a narcoleptic patient falls asleep or wakes up?

Hypnagogic or hypnopompic hallucinations Signup and view all the answers

Which sleep stage is characterized by theta waves and is often the lightest stage of sleep?

Stage 1 Signup and view all the answers

What characterizes insomnia?

Difficulty falling asleep or staying asleep lasting at least 1 month. Signup and view all the answers

In which population is insomnia present?

At least 30% of the population. Signup and view all the answers

Which neurotransmitter is associated with increased sleep efficiency?

Serotonin Signup and view all the answers

How does REM sleep latency differ between depressed young adults and typical young adults?

It is longer in depressed individuals. Signup and view all the answers

What is a common effect of damage to the dorsal raphe nuclei?

Decreased sleep efficiency and REM sleep. Signup and view all the answers

What effect do increased levels of norepinephrine have on sleep?

They decrease both sleep efficiency and REM sleep. Signup and view all the answers

What is a characteristic of sleep in elderly adults compared to typical young adults?

Increased sleep latency. Signup and view all the answers

Which condition is classified as a breathing-related sleep disorder?

Sleep apnea Signup and view all the answers

What is a primary characteristic of sleep terror disorder?

The person cannot be awakened and has no memory of having a dream Signup and view all the answers

Which sleep disorder is characterized by repetitive frightening dreams that cause awakenings?

Nightmare disorder Signup and view all the answers

What type of sleep disorder occurs when a person cannot sleep at appropriate times?

Circadian rhythm sleep disorder Signup and view all the answers

What treatment is commonly used for nocturnal myoclonus?

Benzodiazepine or dopaminergic agents Signup and view all the answers

What is a symptom associated with Restless Legs Syndrome?

Uncomfortable sensations necessitating movement Signup and view all the answers

What distinguishes Kleine-Levin syndrome from other sleep disorders?

Recurrent excessive sleepiness not relieved by naps Signup and view all the answers

What is bruxism and what stage of sleep does it occur in?

Tooth grinding during sleep occurring in stage 2 Signup and view all the answers

Which DSM-5 classification includes sleep-wake disorders?

All of the above Signup and view all the answers

Study Notes

Circadian Cycle

Humans have a natural circadian rhythm that is closer to 25 hours than 24 hours
The circadian rhythm is independent of external cues like light and dark

Awake State

The awake state is characterized by beta and alpha brain wave activity
Beta waves are associated with active mental concentration and are observed primarily over the frontal lobes
Alpha waves are associated with relaxation with closed eyes and are observed primarily over the occipital and parietal lobes
The time it takes to fall asleep is typically less than 10 minutes

Sleep State

Sleep is characterized by distinct changes in brainwave patterns
Sleep is divided into two main phases: REM sleep and non-REM sleep
Non-REM sleep is further divided into four stages (1-4)
Sleep architecture refers to the cyclical pattern of sleep stages throughout the night.
Sleep architecture changes with age; older adults tend to have less REM sleep and slow-wave sleep and more awakenings
Sedatives, such as alcohol, barbiturates, and benzodiazepines, reduce REM sleep and slow-wave sleep
Delta sleep, the deepest stage of sleep, is most prevalent during the first half of the sleep cycle
REM sleep is prolonged during the second half of the sleep cycle
REM sleep is associated with increased brain and cardiovascular activity, including vivid dreaming, penile and clitoral erections, and lack of muscle movement
After sleep deprivation, REM sleep is increased the following night (REM rebound)

Sleep Architecture in a Typical Young Adult

The typical sleep cycle of a young adult progresses through the following stages: Awake, REM, Stage 1, Stage 2, Stage 3, Stage 4, REM, Waking, REM, Waking.

Electroencephalographic Tracings and Characteristics of the Awake State and Sleep Stages

Awake: Beta waves (14-30 cps) and Alpha waves (8-13 cps) are observed. Associated with active mental concentration and relaxation with closed eyes, respectively.
Stage 1: Theta waves (4-7 cps) are observed. This stage is characterized by light sleep, decreased muscle activity, and reduced heart rate and breathing.
Stage 2: Sleep spindles (13-16 cps) and K-complexes are observed. This stage is the longest sleep stage and is associated with bruxism.
Stages 3 & 4: Delta waves (1-3 cps) are observed. These are the deepest stages of sleep, characterized by decreased muscle activity, reduced brain activity, and slow breathing. Sleep disorders such as night terrors, sleepwalking, and bed-wetting may occur during these stages.
REM: "Sawtooth", beta, alpha, and theta waves are observed. This stage is characterized by vivid dreams, increased brain and cardiovascular activity, and paralysis of skeletal muscles.

Narcolepsy

Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness, despite normal sleep duration at night.
Nighttime sleep in narcolepsy is characterized by: decreased sleep latency, short REM latency, less total REM sleep, and fragmented REM sleep.
The characteristics of REM sleep (paralysis, nightmares) can intrude into the awake state, resulting in:
- Hypnagogic hallucinations: Strange perceptual experiences occurring as the patient falls asleep.
- Hypnopompic hallucinations: Strange perceptual experiences occurring as the patient wakes up.
- Cataplexy: Sudden collapse due to loss of muscle tone triggered by strong emotions.
- Sleep paralysis: Inability to move after waking up.
Narcolepsy is uncommon and often occurs in adolescents and young adults.
It may have a genetic component.
Daytime naps can help improve symptoms and reduce sleepiness.

Sleep Disorder Characteristics

Sleep terror disorder: Repetitive episodes of fear and screaming during sleep, occurring mainly in children. The individual is not easily awakened and has no memory of the event. Occurs during delta sleep.
Nightmare disorder: Repetitive, frightening dreams causing awakenings. The person usually remembers the nightmare and it occurs during REM sleep.
Sleepwalking disorder: Repetitive walking during sleep, no memory of the episode upon waking. It starts in childhood and occurs during delta sleep.
Circadian rhythm sleep disorder: Difficulty sleeping at the desired times.
- Delayed sleep phase type: Difficulty falling asleep and waking up at desired times.
- Jet lag type: Occurs after changing time zones.
- Shift work type: Occurs due to inconsistent work schedules.
Nocturnal myoclonus: Repetitive muscle contractions in the legs, causing awakenings. It is treated with benzodiazepines, quinine, or antiparkinsonian agents.
Restless legs syndrome: Uncomfortable sensation in the legs requiring movement. It can cause difficulty falling asleep and awakenings. It may be associated with aging, Parkinson's disease, pregnancy, and kidney disease. Treatment includes antiparkinsonian agents, iron supplements, or magnesium supplements.
Kleine-Levin syndrome and menstrual-associated syndrome: Recurrent episodes of excessive sleepiness lasting for weeks to months. Sleepiness is not alleviated by naps.
Sleep drunkenness: Difficulty waking up fully after adequate sleep.
Bruxism: Tooth grinding during sleep, which can lead to tooth damage and jaw pain. Treatment includes night guards or orthodontia.

Classification of Sleep Disorders

The DSM-5 categorizes sleep disorders into three main categories:
- Sleep-wake disorders: Problems with the timing, quality, or amount of sleep. Examples include insomnia, hypersomnia, and narcolepsy.
- Breathing-related sleep disorders: Disorders affecting breathing during sleep such as sleep apnea.
- Parasomnias: Abnormalities in behavior or physiology during sleep. Examples include bruxism, sleepwalking, sleep terrors, REM sleep behavior disorder, and nightmare disorder.

Insomnia

Insomnia is defined as difficulty falling or staying asleep for at least one month, leading to daytime sleepiness or problems with social or occupational functioning.
It affects at least 30% of the population.

Summary of Sleep Characteristics in Typical, Depressed, and Elderly Individuals

Sleep Latency:
- Typical Young Adult: Approximately 10 minutes
- Depressed Young Adult: Greater than 10 minutes
- Typical Elderly Adult: Greater than 10 minutes
REM Latency:
- Typical Young Adult: Approximately 90 minutes
- Depressed Young Adult: Approximately 45 minutes
- Typical Elderly Adult: Approximately 90 minutes
Sleep Efficiency:
- Typical Young Adult: Approximately 100%
- Depressed Young Adult: Less than 100%
- Typical Elderly Adult: Less than 100%
Percentage of Delta Sleep:
- Typical Young Adult: Approximately 25%
- Depressed Young Adult: Less than 25%
- Typical Elderly Adult: Less than 25%
Percentage of REM Sleep:
- Typical Young Adult: Approximately 25%
- Depressed Young Adult: Greater than 25%
- Typical Elderly Adult: Less than 25%

Neurotransmitters and Sleep

Acetylcholine (ACh): Increased levels in the reticular formation promote both sleep efficiency and REM sleep. ACh levels decrease with age and are reduced in Alzheimer's disease.
Dopamine: Increased levels reduce sleep efficiency. Antipsychotics, which block dopamine receptors, may improve sleep in those with psychosis.
Norepinephrine: Increased levels decrease sleep efficiency and REM sleep.
Serotonin: Increased levels promote both sleep efficiency and delta sleep. Damage to the dorsal raphe nuclei which produce serotonin reduces both of these measures. Antidepressants which increase serotonin availability can improve sleep efficiency in depressed individuals.

Management of Major Sleep Disorders

Insomnia:
- Avoid caffeine before bed
- Develop a consistent bedtime routine
- Maintain a regular sleep schedule
- Exercise regularly, but not close to bedtime
- Practice relaxation techniques
- Consider using sleep agents, antidepressants, or antipsychotics in limited cases.
Breathing-Related Sleep Disorder (Obstructive Sleep Apnea):
- Weight loss if overweight
- Continuous Positive Airway Pressure (CPAP)
- Breathing stimulants such as medroxyprogesterone acetate, protriptyline, or fluoxetine.
Narcolepsy:
- Stimulant agents such as modafinil or methylphenidate
- Sodium oxybate or antidepressants for cataplexy
- Scheduled daytime naps.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fascinating concepts of circadian cycles and sleep states in this quiz. Learn about the human body's natural rhythm, brainwave activity during waking and sleeping states, and the architecture of sleep. Test your knowledge on the complexities of sleep phases, including REM and non-REM sleep.