Sleep Flashcards
Learn sleep
What’s N1 of the sleeping cycle?
Stages of daydreaming
- Beginning to fall asleep
- alpha waves (8-14 cycles/sec)
- theta waves (4-7 cycles/sec)
What’s the N2 of the sleeping cycle?
Light sleep, body temp dropping
- Heart rate slows down
- Rhythmic brain wave activity
- Sleep spindles
What’s the N3/4 of the sleeping cycle?
Delta waves (0-4 cycles/sec)
- Blood pressure drops
- Slower breathing
- Energy restored
- Hormones released for growth development.
What is REM?
Dreams, rapid eye movement.
- Increased respiration rate, brain activity,
- Paradoxical sleep
- Voluntary muscles paralyzed
What’s the average sleep needed by all ages?
Depending on age. 7.5 hours to 18 hours.
- Adults +18: 7.5-9 hours
- Newborns - 2 months: 12-18 hours.
Systems involved in dreaming.
Primary visual cortex, secondary visual system, limbic system, dorsolateral prefrontal cortex, release of norepinephrine, serotonin, and histamine.
What is Lucid dreaming?
Consciously aware in your dreams, aware that you are dreaming.
What can damage to the brainstem cause?
Can induce sleep or coma. Brainstem and basal forebrain involved with ACh.
Explain the initiation of non-REM.
General decrease in firing rates of most brainstem modulatory neurons.
- Subset of cholinergic neurons in basal forebrain increase firing rate at non REM onset, silent during wakefulness
- Sleep spindles and delta rhythms produced by thalamic potentials.
What’s going on during REM sleep?
Many cortical areas as active during sleep as during wakefulness.
- Motor cortex: a few muscles in eye, inner ear, respiration.
- Brainstem systems inhibit spinal motor neurons (REM atonia).
- Low frontal lobe activity
- Increased limbic activity
- Increase in exstrastriate activity.
What are the sleep promoting factors?
Immune system involvement
- muramyl peptides (non REM)
- interleukin-1 peptide
- adenosine
- antagonists (caffeine), inhibits modularly systems for ACh, NE, and 5-HT.
Are there changes in Gene Expression?
Most genes expressed equally during both sleep and awake states. Some specific genes change levels of expression.
- Highly expressed during awake state: immediate early genes and mitochondrial genes.
What is apnea?
Sleep related breathing disorders.
What is phase disorder?
Circadian rhythm disorders
What is parasomnias?
Disorders that involve abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams.
What are dysomnias?
Insomnia and hypersomnia.
What is unihemispheric sleep?
Dolphins, ducks, and iguanas can rest one half of brain while keeping other half active/awake. In part to ward for predators.
What is sleep terror (pavor nocturnus)?
Occurs during NREM sleep (N3/4) early in the night( high delta activity, slow wave sleep). Intense fear activates autonomic processes (higher heart rate, fight or flight).
What is sleep walking (somnambulism)?
Happens during NREM sleep (N3/4) and early in the night (high delta activity, slow wave sleep). Activities from sitting up to dressing etc. Can incur nocturnal enuresis (bed wetting).
- More observed in children 6-12.
- Appears to run in families.
- Diagnosis: polysonogram.
What are circadian rhythms?
influences sleep, eating, temperature, metabolism, protein syntehsis.
- Somewhat longer than 24 hours for most people.
- Women ~ 6 minutes shorter than man.
- Some women shorter than 24 hours
- Mutations can shorten to 19 hours.
Influences cognitive tasks such as attention, executive functions.
What’s the suprachiasmatic nucleus (SCN) of the hypothalamus?
Master clock
- External stimuli entrain
- Allow resetting of internal clock
- Melanopsin retinal ganglion cells project via retinohypothalamic tract.
- Blue light (~446-477 nm) most effective zeitgeber.
- Other zeitgebers include social activity, temperature, sound, physical activity.
How does bright light affect the circadian rhythm?
Bright light in evening phase: delays clock
- Bright light in morning phase: advances clock
What does melatonin do?
Produced by pineal gland
- Encourages sleep
- Secreted at night
- Secretion inhibited by bright light
- Induces phase shifts in circadian rhythm.
- Taken in late afternoon, advances circadian rhythm and increases quality of sleep.
What are positive regulators involved in the circadian rhythm?
- Self-regulating feedback cycle.
Clock, BMAL/Cycle, Bind to promotors and induce transcription of negative regulators.
Explain the negative regulators.
Per, Tim, Cry
- Transcribed during day and translocated to cytoplasm in early evening
- Kinases phosphorylate and cause degradation
- Later in evening, dimerize and increase stability
- Return to nucleus and inactivate positive regulators
- At dawn, dimers destabilize and positive regulators restored.
Circadian Rhythm’s effects on Cognitive performance.
Bright light exposure (~460 nm) increases alertness and motor performance
- Best cognitive performance in afternoon
- Better cognitive performance associated with higher core body temperature.
What is a Chronotype?
Attribute of human beings reflecting at what time of the day their physical functions (hormone level, body temperature, cognitive faculties, eating and sleeping) are active, change or reach a certain level influenced by age and affects medical test results and treatments.
- Larks: older individuals
- Owls: adolescents, greater susceptibility to depression and other disorders, and rhythms in skin more difficult to entrain.
What are some problems correlated with sleep deprivation?
School performance, difficulties in attention and impulse control, increased risk of crashes and risk-taking behavior in teens, increased reaction time on harsh-braking test.
- Insufficient sleep in about 25% of population.
What are the functions of sleep?
Restoration: anabolic processed increased during sleep.
Energy Conservation: ATP levels increase during sleep.
Memory Consolidation: SWS improves declarative memory, REM improves procedural memory, sleep scores account for ~ 69% of variance in memory consolidation.
What is synaptic resetting?
A function of sleep.
- SWS suppresses synaptic connectivity
- Most synapses silenced
- Only strongest connections (learning) remain, emphasizing learning from the day.
What are the hormones that stimulate wakefulness?
Histamine, dopamine, acetylcholine, norepinephrine, orexin/hypocretin: absence associated with narcolepsy, exogenous administration promotes waking, projects to other arousing networks.
What hormones decrease wakefulness?
Adenosine: antagonized by caffeine
- GABA
Where does the SCN project?
To hypothalamus, brainstem, and vagus nerve nucleus.
What does mutation in DEC2 gene cause?
In <3% of population, allow full rest with less than 6 hours of sleep.
