22-Sleep Flashcards
Define Sleep
Unconsciousness from which the person can be aroused by sensory or other stimuli.
Sleep is:
• A behavioral state
• Natural part of our lives
• Requiredactivity,notanoption
• Highly organized following regular cyclic pattern
• Caffeine/stimulants cannot substitute for sleep
effects of sleep deprivation
- apparent state of paranoia
- hallucinations
- impaired cognition
- diverse physiological signs
- deterioration of immune system
*can maybe go a little more than 10 days without sleep before dying
as you become sleep deprived what happens to alertness and temperature
less alert and your temperature also slightly decreases over time
what type of sleep is associated with an increased risk of morbidity and mortality
too much and too little sleep
-too much sleep is also associated with diabetes and hypertension
best average number of hours we need to sleep per night
7.5 is the perfect number of hours
functions of sleep
- Restoration and recovery of body systems
- Replenish energy stores
- Repairing body systems after periods of energy consumption and tissue breakdown
- Conserve energy
Rapid Eye Movement (REM) sleep is needed for
– Memory consolidation
– Reinforcement of learning
– Helping to clear unneeded memories
*During non-REM sleep there is a flushing out of brain waste products with CSF
—None of these explain why sleep is better than just resting while awake, we dont know that yet.
Motor activities during sleep
NREMSleep
– Few motor events
– Body repositioning
REMSleep
– Paralysis
• Postsynaptic inhibition of motorneurons
• Hyperpolarization of motoneuron membranes
– Phasic events
• Rapid eye movements
• Muscle twitches
NREM and REM Sleep Comparison in the Central Nervous system
NREM Sleep
- Discharge rate of neurons
- Cerebral glucose utilization decreased
REM Sleep
- Discharge rate of neurons increased (Rapid eye movements)
- Cerebral glucose utilization and blood flow increased
Sleep architecture (time in each stage)
- Alternating between NREM and REM sleep
- Brief arousals
- Deepest NREM sleep early in the night
- REM longer as the night progresses
- Age-dependent changes
Sleep architecture: age differences
Quantification: Total sleep time and percent of REM sleep decrease with age
Note:
• High percent of REM sleep in infants
• Fragmented and relatively reduced sleep time in the elderly
• Dominance of REM in infants is thought to reflect synaptic and brain development
sleep load
proprensity to go to sleep (this load is built throughout the day and goes away when you sleep)
alert signal
counters the sleep load and then the alert signal drops off while youre sleeping which alleviates the sleep load
two factors of sleep and awake
- homeostatic
2. circadian
Sleep regulation: circadian factors
Internal biological clock
– Sleepy at night
– Awake during the day
Approximate 24-hour period
Hypothalmic suprachiasmatic nucleus (SCN)
Regulates endogenous biological rhythms
Entrained to match the day length by retina input to the SCN.
environmental cues and sleep
natural rhythm over scn is 26 hours but in reality its 24 hours cause of inputs we receive from external cues
sleep regulation with melatonin
- Melatonin increases at night
- Can produce shifts in circadian rhythms
- Is thought to promote sleep
what contributes to sleep and wake regulation
neuromodulators (they change during sleep)
- Serotoninergic neurons (in raphe pallidus )
- Noradrenergic neurons (in locus coeruleus)
- Decrease activity from wakefulness during sleep
- Pontine LDT/PPT & FTG increase ACH to mediate REM
- Wakefulness promoting substances: Serotonin, Norepinephrine, Histamine
- Sleep promoting substances: Opioids, GABA
- REM sleep mediated by pontine ACH release
wake promoting factors
- increase excitatory neuromodulators
- increase circadian
- decrease homeostatic
nREM promoting factors
- decreased excitatory neuromodulators
- decreased circadian
- increased homeostatic
REM promoting factors
- decreased excitatory neuromodulators
- decreased circadian
- increased homeostatic
- increased acetylcholine
what controls neuromodulators
brainstem
what controls circadian and homeostatic factors
hypothalamus
physiologic (breathing) changes from wakefulness to sleep
Ventilatory:
• Reduced ventilation and hypoventilation secondary to reduced neuromodulation during sleep
- Central sleep apnea- Transient cessation of breathing due to dysfunction of respiratory rhythm generator most often caused by opioid-induced increased inhibition
- Obstructive sleep apnea- Respiratory rhythm generator is functional but airway is closed due to lack of genioglossal muscle activity.
- Congenital central alveolar hypoventilation- lack of chemoreceptor excitation results in apnea during sleep
- Sudden infant death syndrome (SIDS)- dysfunctional serotonin system results in attenuated chemoreceptor activity
hemodynamic changes during sleep
- Result from alteration in autonomic system
- Parasympathetic activity predominates
- Heart rate and cardiac output decrease
- Cerebral blood flow decreases in NREM, increases during REM
- During phasic REM, blood pressure and heart rate are unstable due to phasic vagal inhibition and sympathetic activation
- Decrease in total vascular resistance during sleep
body temperature and sleep
- Begins to fall at sleep onset (1-20 Celsius)
- Lowest Temperature during the 3rd NREM/REM cycle
- During REM thermoregulation inoperative
- Sweating and shivering seen in NREM but not REM
what happens to the limb muscles while you sleep (neuromuscular)
• Muscle tone maximal awake, slightly decreased during NREM, absent during REM sleep (save the diaphragm).
what happens to upper airway muscles while you sleep (neuromuscular)
- Reduction of dilator (genioglossal) activity during NREM further reduction during REM
- Increased in upper airway resistance and narrowing of the upper airway space
GI and sleep
GI secretion
- Circadian rhythm
- Peaks between 10:00 p.m. and 2:00 a.m.
- No relationship to different stages of sleep
GI Motility
-Overall inhibition of gastric motor function during sleep
Endocrine: Growth hormone and sleep
- Plasma concentrations peak 90 minutes after sleep onset
- Higher in men than women
- Duration of 1-3 hours, related to SWS
- Sleep deprivation suppresses GH secretion
Endocrine: Parathyroid and sleep
- Increased levels during sleep
* Peaks 2 -4 a.m.
Endocrine: Adenocorticotropic hormone (ACTH) and sleep
- Cortisol decreases with sleep onset
* Cortisol levels lowest in early part of sleep, highest from 4– 8 a.m.
Endocrine: Prolactin and Sleep
- Sleep dependent pattern
- Highest plasma concentrations during sleep
- Levels begin to rise 60-90 minutes after sleep onset
- Higher in women than men
- Peak 5 – 7 a.m.
Endocrine: gonadotropin and sleep
- During pre-puberty and puberty stages in boys and girls, levels increase during sleep
- Plasma testosterone levels rise at sleep onset and continue to rise throughout sleep
- No clear relationship in FHS and LH plasma levels has been found during sleep
Endocrine: thyroid stimulating hormone and sleep
- peak shortly before sleep onset
- TSH secretion is inhibited by sleep
- Greatest inhibition during SWS
Endocrine: Aldosterone and sleep
Increased during sleep
Endocrine: Melatonin and sleep
• Increases in sleep to peak 3 to 5 a.m.
• Highest levels correspond to lowest core body
temperature
Endocrine: Antidiuretic Hormone and sleep
• Episodic secretion, however no relationship to sleep
ultradian rhythm
rhythm occurring within a period of less than 24 hours
