INP final - SLEEP Flashcards
Flashcards for the second half of the INP course. This set will cover SLEEP
What is sleep?
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.
Describe the various sleep stages and how one cycles through those stages during the night.
- Wakefulness
- Non-Rapid Eye movement (NREM, N1-N3)
- REM
How do we cycle through sleep?
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.
What is wakefulness (step in sleep)?
- 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
What is NREM N1 (step in sleep)?
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
What is NREM N2 (step in sleep)?
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%)
What is NREM N3 (step in sleep)?
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
What is REM sleep?
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
How does sleep change during the life cycle?
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
What are circadian rhythms?
- 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.
How are circadian rhythms regulated?
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.
Describe circadian drive for sleep. Understand factors that affect this mechanism and how they influence sleep at night.
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
Describe homeostatic drive for sleep. Understand factors that affect this mechanism and how they influence sleep at night.
- 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
What are subjective ways to measure sleep and diagnose sleep disorders?
Questionnaires assessing:
- Risk of snoring
- Sleepiness
- Insomnia
- Functional outcomes
- Quality of life
What are objective ways to measure sleep and diagnose sleep disorders?
- Polysomnography
- Actigraphy
- Multiple Sleep Latency Test (MSLT)
- Maintenance of Wakefulness Test (MWT)
What is polysomnography?
- 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
What is actigraphy?
- 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
What is a mean sleep latency test?
- 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
Detailed sleep history, which is necessary for clinical sleep studies, consists of:
- 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)
What is obstructive sleep apnea (OSA)?
- 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)
What is insomnia?
- 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
What is narcolepsy?
- 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
What is jet lag?
- 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
What are early/late rhythm phase disorders?
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
