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is a naturally occurring altered state of consciousness characterized by decreases in awareness and responsiveness to stimuli
Polygraph recordings of electrophysiologic changes in brain waves (electroencephalogram [EEG]), eye movements (electrooculogram [EOG]), and muscles (electromyogram [EMG]
Stage 1 -between drowsy and sleep
Stage 2 - bursts of sleep spindles, rolling eye movements and snoring
Stage 3&4 - deep, slow-wave sleep
REM - closely resembles wakefulness
Stage 1 Sleep
lasts a few min - transitional stage between drowsiness and sleep - a shift from alpha waves to low-voltage, fast theta waves on the EEG. Muscles relax, respirations become even, and pulse rate decreases
Stage 2 Sleep
a relatively light sleep from which the person is easily wakened. Bursts of sleep spindles appear on the EEG - Rolling eye movements continue, and snoring may occur
Stage 3&4 Sleep
"deep" sleep, sometimes termed slow-wave sleep or delta sleep after characteristic waves seen on the EEG - muscles are relaxed, but muscle tone is maintained; respirations are even; and blood pressure, pulse, temperature, urine formation, and oxygen consumption by muscle decrease.
REM Stage Sleep
closely resembles wakefulness except for very low muscle tone, indicated by a reduction in amplitude of the EMG - Blood pressure and pulse rate show wide variations and may fluctuate rapidly. Respirations are irregular, and oxygen consumption increases. Thermoregulation is lost. Vaginal secretions increase in women, and erections may occur in men. Dreams occurring during REM sleep tend to be vivid and implausible, sometimes including a sense of being unable to move.
a rhythmic pattern of approximately 90-minute cycles during which people progress in sequence through the sleep stages
Reticular Activating System (RAS)
consists of a network of interconnecting neurons in the medulla, pons, and midbrain, with projections to the spinal cord, hypothalamus, cerebellum, and cerebral cortex - fills in the spaces in the brainstem among the major tracts, bringing in sensory messages and relaying motor ones
a major neurotransmitter associated with sleep - produced in the raphe nuclei in the brainstem, serotonin is derived from its precursor, tryptophan
Psychological Functions of Sleep
Sorting and discarding of neurophysiologic data - Character reinforcement and adaptation for mental and emotional stability
an urge of varying intensity to go to sleep. It may occur in response to too little or too much sleep or to lack of adequate sensory stimulation
a subjective state of weariness in which intense or rapid tiring accompanies physical activity. It is a common human response to illness, suggesting the need to conserve energy through rest and sleep.
those who sleep for less than 6 hours in 24) tend to be efficient, hard-working people
(those who sleep for more than 9 hours in 24) have a higher percentage of REM sleep, and there is some suggestion that as a group they are more creative - tend to die at a younger age
synthesized in the pineal gland during the hours of darkness, has an apparent rhythm-setting function closely related to light conditions
suprachiasmatic nucleus (SCN)
located above the optic chiasm in the anterior hypothalamus, functions essentially as the "clock" for most circadian rhythms by relaying information from the retina to the pineal gland
Growth hormone and prolactin levels (sleep)
are closely tied to actual sleep time, changing immediately in relation to variations in the sleep period, irrespective of light-dark conditions. Secretion of both hormones increases early in the sleep period
Adrenocorticotropic hormone secretion from the pituitary
is high during the early part of the sleep period, and levels of cortisol, its target hormone from the adrenal cortex, rise toward the end of the nocturnal sleep period
which hormonal levels adjust at different rates to alterations in the timing of the sleep period
Lifespan Sleep Patterns
Infants REM sleep is 50% higher than adults
REM content gradually drops to about 20% at puberty
Older Adults phase advance
associated with the loss of core sleep and reflected in impaired cerebral functioning
sleep and Shift Work
The accumulated sleep debt may compromise clinical judgment and decision making, an increasing concern in healthcare in terms of patient safety
Exercise and sleep
Habitual exercise contributes to deeper and longer sleep. In physically fit people, light-intensity exercise seems to decrease sleep latency, and intensive exercise increases the proportion of slow-wave sleep
Lifestyle, Habits and sleep
bedtime rituals become habits - A regular time of rising is one of the most effective means of improving sleep quality and synchronizing circadian rhythms with clock time.
sleeping pills - used to decrease sleep latency and improve sleep maintenance, are among the medications most prone to disturb sleep architecture. REM sleep is most vulnerable.
Medications and Chemicals (sleep)
hypnotics - alcohol - morphine - antidepressants - phenytoin (epilepsy) - caffeine - nicotine
Manifestations of Altered Sleep
s/s associated with sleep deprivation are fatigue, headache, nausea, increased sensitivity to pain, decreased neuromuscular coordination, general irritability, and inability to concentrate. Eventually, disorientation and hallucinations
persistent insomnia associated with somatized tension and learned sleep-preventing associations
a disorder of excessive daytime sleepiness characterized by short, almost irresistible daytime sleep attacks, usually lasting 10 to 15 minutes, and abnormal manifestations of REM sleep
recurrent periods of absence of breathing for 10 seconds or longer, occurring at least five times per hour
Obstructive Sleep Apnea
involves collapse of the upper airway despite respiratory effort
- Common treatments include continuous positive airway pressure applied through a nose mask and surgical reconstruction of the upper airway with removal of most of the uvula, posterior portion of the soft palate, and tonsils
Untreated Sleep Apnea
can increase the chance of having high blood pressure and even a heart attack or stroke & can also increase the risk of diabetes and for other accidents
occurs because of neurogenic failure to trigger respiratory effort - most commonly seen with neurologic conditions such as stroke or brainstem involvement. Severely affected clients may require ventilatory support at night.
activities that are normal during waking but abnormal during sleep, such as somnambulism, talking, and enuresis - usually occur during slow-wave sleep - most common in children
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