INP final - SLEEP

Question 1

What is sleep?

Answer 1

Behavioral: Sleep is a reversible behavioral state of perceptual disengagement from and unresponsiveness to the environment

Neural/Physiological: A dynamic and actively produced brain state, with accompanying changes to physiology.

Question 2

Describe the various sleep stages and how one cycles through those stages during the night.

Answer 2

• Wakefulness
• Non-Rapid Eye movement (NREM, N1-N3)
• REM

Question 3

How do we cycle through sleep?

Answer 3

During the night, you start with wakefulness, REM, NREM. As the night progress you experience more REM/dreaming sleep and less deep sleep of N3.

Question 4

What is wakefulness (step in sleep)?

Answer 4

• daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world such as communication, ambulation, eating, and sex.
• less than 5% of the night

Question 5

What is NREM N1 (step in sleep)?

Answer 5

Very light sleep

• Transition from Wake to Sleep
• Drift in and out of sleep, awaken easily
• Hypnagogic jerk: Sense of falling followed by sudden muscle contraction
• Slowed eye movement
• 2% to 5% of sleep

Question 6

What is NREM N2 (step in sleep)?

Answer 6

Relatively light but maintained sleep

• Brain activity relatively slower
• Breathing and heart rate slowed
• Maintained sleep
• No eye movement
• Spindles
• most of sleep (45% to 55%)

Question 7

What is NREM N3 (step in sleep)?

Answer 7

Deep Sleep (Slow wave sleep)

• Lower brain activity
• High awakening threshold
• Restoration of body
• Delta waves
• No eye or body movement
• 15% to 25% of sleep

Question 8

What is REM sleep?

Answer 8

Rapid eye movement

• Very active brain activity
• Dreams
• Paralyzed body
• EEG activation
• Episodic bursts of REMs
• 20% to 25% of sleep, occurring in four to six discrete episodes

Question 9

How does sleep change during the life cycle?

Answer 9

As we age generally we don’t need as much sleep.

as newborns (0-2 months) it is recommended to get about 12-18 h of sleep; as adults, 7-9hr is optimal.

we ↓ the amount of slow wave sleep we get and ↑ WASO (wake after sleep onset), which is a better reflection of sleep fragmentation

circadian rhythms become less robust as we age.

↑ in sleeping disorders, like insomnia, as we age

Question 10

What are circadian rhythms?

Answer 10

• The body’s rhythms that runs on about 24hr cycle. In general this is the body’s biological clock.
• Circadian rhythms refer to changes in things like hormones, behaviors, and happenings in our bodies across the 24 hour day.

Question 11

How are circadian rhythms regulated?

Answer 11

Regulated by the Circadian Pacemaker

Characteristics of circadian pacemakers:
- Endogenous rhythmicity that persist independent of periodic changes in the environment
- A near 24-hr period
- The capacity for environment input to modify of reset timing or phase of the rhythms (entrainment)
Is the suprachiasmatic nucleus in humans

The SCN receive inputs from the external environment via the eyes and feed forward onto other brain regions to regulate circadian variation of behaviors physiology, neuroendocrine secretions, etc.

Question 12

Describe circadian drive for sleep. Understand factors that affect this mechanism and how they influence sleep at night.

Answer 12

Circadian forces maintain sleep after homeostatic needs are fulfilled and prevent sleep during the day as they oppose homeostatic forces

HORMONES
Melatonin:the hormone of darkness; helps the body to fall asleep.
Cortisol: stress hormone; helps the body wake up and alertness

BODY TEMPERATURE
Core body temp is at its lowest during sleep period. Core temp has an inverse relationship with melatonin and sleep propensity

Question 13

Describe homeostatic drive for sleep. Understand factors that affect this mechanism and how they influence sleep at night.

Answer 13

• Homeostatic forces drive sleep onset and are dissipated early
• Process S is the sleep pressure that builds up during wakefulness and dissipates exponentially during sleep.
• Process C is the circadian process is related to time of day, irrespective of previous sleep duration and opposes the homeostatic process

Question 14

What are subjective ways to measure sleep and diagnose sleep disorders?

Answer 14

Questionnaires assessing:
- Risk of snoring

• Sleepiness
• Insomnia
• Functional outcomes
• Quality of life

Question 15

What are objective ways to measure sleep and diagnose sleep disorders?

Answer 15

• Polysomnography
• Actigraphy
• Multiple Sleep Latency Test (MSLT)
• Maintenance of Wakefulness Test (MWT)

Question 16

What is polysomnography?

Answer 16

• Objective assessment of sleep duration, sleep staging and sleep disorders
• Diagnostic for obstructive sleep apnea, narcolepsy, periodic limb movement disorder, restless leg, circadian rhythm phase disorder.
• Provides info about how much time spent in stage 1,2,3 and REM sleep
• Provides information on time spent in stage 1, 2, 3, and REM sleep
• EEG distinguishes stages of NREM, EOG measures eye movement, sign of REM sleep, and EMG at chin useful for staging REM and at the anterior tibilias for diagnosing PLMD

Question 17

What is actigraphy?

Answer 17

• Objective assessment of of total sleep time, sleep efficiency and wake after sleep onset. Used in conjunction with a sleep diary.
• Assesses sleep over 7-14 days to determine patterns of sleep for diagnosis of circadian rhythm phase disorder
• Helpful to monitor treatment in response to insomnia and sleep in difficult populations such as children and people with dementia

Question 18

What is a mean sleep latency test?

Answer 18

• Assesses propensity to fall asleep during the day
• Used to diagnosis narcolepsy and sleep onset REM
• Mean Wakefulness Test: assesses ability to remain awake during the day. Used to assess response to treatment
• Various sleeping scales/questionnaires
• Assesses subjective feelings of sleep quality. Measures the impact of daytime sleepiness on activities of day living. And assess improvements in patient’s excessive sleepiness

Question 19

Detailed sleep history, which is necessary for clinical sleep studies, consists of:

Answer 19

• chief sleep complaint
• activities before bedtime
• bedtime
• sleep latency
• awakenings
• time out of bed
• wake time
• rise time
• naps (number and duration)
• symptoms (sleepiness, fatigue) establishment of typical patterns and deviations from patterns (eg. Weekends)

Question 20

What is obstructive sleep apnea (OSA)?

Answer 20

• Interruptions in breathing during sleep that cause arousals and daytime sleepiness
• Diagnosed by: Polysomnography (apena/hypopnea 5-15 mild, 15-30 moderate, >30 severe)
• Associated with increased risk of chronic diseases (heart disease, arrhythmias, hypertension, diabetes)
  Treatment: oral appliances, continuous positive airway pressure (CPAP)

Question 21

What is insomnia?

Answer 21

• Difficulty initiating or maintaining sleep, early morning awakening, daytime impairment
• Most prevalent sleep disorder
• Risk factors: age, female, shift work, unemployment, low SES, co-morbidities
• Diagnosis: difficulty: initiating sleep, maintaining sleep, unintended early morning sleep. Results in daytime impairment. Symptoms occur despite opportunity for sleep
• Treatment: psychological and behavioral intervention, benzodiazepine receptor agonist, off-label: anti-depressants, anti-epileptic drugs

Question 22

What is narcolepsy?

Answer 22

• Excessive daytime sleepiness & intermittent manifestation of REM sleep during daytime/wake
• Treatment goal is to alleviate daytime sleepiness.
• Stimulant drugs can be used. Scheduled naps can be effective adjunct therapy

Question 23

What is jet lag?

Answer 23

• social or travel
• If time at destination is brief, keep home-based sleep hours to reduce sleepiness
• Melatonin at appropriate time
• Caffeine may be indicative

Question 24

What are early/late rhythm phase disorders?

Answer 24

Advance Sleep-Wake phase disorder:
- Advance of major sleep episode relative to desired time. Treatment is light therapy to delay melatonin release

Delayed Sleep-Wake Phase Disorder:

• Delay of major sleep episode relative to desired tie or timing required to attend social, educational, or occupational activities
• Treatment with timed melatonin or post-awakening light exposure (kids)

Non-24-h sleep-wake:
- Failure to have a 24-h light/dark cycle/clock. Usually sleep-wake patterns show progressive delay. Often seen in blind people.

Shift-Work:

• Insomnia disorder and excessive sleepiness due to inability to adjust to night shift or rotating shifts.
• Treatment includes napping before or during scheduled work, time light exposure at work and light restriction in the morning. Administer melatonin before daytime sleep

Question 25

How does sleep duration influence energy balance?

Answer 25

• Shorter sleep increases energy expenditure
• Energy intake favors partial sleep deprivation, energy expenditure favors partial sleep deprivation (intake was more tho).
• Overall sleep-restriction has an increase of weight change compared to control.
• Sleep restricted group ate more food/energy intake, sleep for 4hr, and resulted in an increase in body weight

Question 26

How does sleep duration influence cardiometabolic risk factors?

Answer 26

Diabetes risk increased in:
- Insomnia symptoms and sleep disordered breathing

Hypertension risk increased in:
- Insomnia symptoms, sleep disordered breathing

CVD risk increased in:
- Insomnia & MI (stronger in women), insomnia & stroke (incident CVD & CVD mortality), sleep disordered breathing & stroke

Question 27

Why is food intake increased with shortened sleep duration?

Answer 27

• Changes in hormones
• Delay in food intake
• Impulse control
• Decision-making
• Reward valuation of food

Question 28

Those that sleep restricted are found have an ___ in ghrelin and _______ in leptin hormones.

Answer 28

increase in ghrelin (hunger hormone)

decrease in leptin (satiety hormone)

Question 29

How can sleep loss lead to hypertension?

Answer 29

sleep loss → increased sympathetic nervous activity, increased evening cortisol, and increased nighttime GH

increased sympathetic nervous activity, increased evening cortisol, and increased nighttime GH → HYPERTENSION

Question 30

How can sleep loss lead to diabetes?

Answer 30

sleep loss → increased sympathetic nervous activity, increased evening cortisol, and increased nighttime GH

increased sympathetic nervous activity, increased evening cortisol, and increased nighttime GH → increased insulin resistance and decreased glucose tolerance

increased insulin resistance and decreased glucose tolerance → DIABETES

Question 31

How can sleep loss lead to overweight/obesity?

Answer 31

sleep loss → increased ghrelin and orexin, decreased leptin, later time to eat, lower EE

increased ghrelin and orexin, decreased leptin, later time to eat, lower EE → possible increases in appetite

increases in appetite → sustained excess energy intake

sustained excess energy intake → OVERWEIGHT/OBESITY

Question 32

How does sleep affect the brain?

Answer 32

Sleep affects:
- Memory consolidation

• Cognitive function in adolescents,
• Impulse control
• AD risk
• Stroke

sleep loss → altered circardian rythms which

Question 33

How does sleep affect the kidney?

Answer 33

sleep loss → increased SNS → Na retention in kidneys