2H. Stages of Sleep and Brain Mechanisms Flashcards
a state that the brain actively produces, characterized by decreased activity and decreased response to stimuli
sleep
an extended period of unconsciousness caused by head trauma, stroke, or disease
coma
vegetative state; condition that alternates between sleep and moderate arousal, but even during the more aroused state, the person shows no awareness of surroundings and no purposeful behavior
unresponsive wakefulness syndrome
brief periods of purposeful actions and a limited amount of speech comprehension; can last for months or years
minimally conscious state
condition with no sign of brain activity and no response to any stimulus
brain death
physicians usually wait until someone has exhibited no sign of brain activity for ___ before pronouncing brain death at which point most people believe it is ethical to remove life support
24 hours
human brain most commonly produced when a person is awake but relaxed with eyes closed; often experienced before falling asleep
alpha waves
waves the human brain most commonly produces; amplitude generally increases as a person becomes tired and enters the first stage of sleep, then decreases as they enter the 2nd and 3rd stages of sleep
beta waves
occur during the 2nd stage of sleep; also called “sigma waves”; can be either slow or fast
sleep pindles
sharp waves that stand out from background brain wave patterns and last at least half a second; appear during
stage 2 sleep
K-complexes
slower brain waves that gradually replace alpha waves as a person transitions from a relaxed state to being asleep
theta waves
the slowest brain waves and they primarily occur during deep sleep, the 3rd stage of sleep
delta waves
lasts 1-7 minutes, with light sleep, slight body movements, and easy awakenings
stage 1 (N1)
body relaxes, temperature drops, breathing and heart rate slow; brain activity decreases with bursts of resistance to waking, lasting 10-25 minutes and making up about half of total sleep time
stage 2 (N2)
hardest to wake from, with slow delta waves; muscles, pulse, and breathing slow further; crucial for recovery, immune function, memory, and creativity; lasts 20-40 minutes, decreasing later in the night
stage 3 (N3)
brain activity increases near wakefulness; body is temporarily paralyzed except for eye and breathing muscles; essential for memory, learning, and creativity; vivid dreams occur; starts ~90 minutes after sleep begins, lengthens through the night, making up 25% of total sleep
REM sleep
REM sleep in species without eye movements
paradoxical sleep
has both neurons that promote wakefulness and those that promote sleep
hypothalamus
drugs produce drowsiness
antihistamine
provide axons that extend throughout the thalamus and cerebral cortex some of them increasing wakefulness and other inhibiting it
basal forebrain cells
stimulates the basal forebrain cells
acetylcholine
active in response to meaningful events and facilitates attention and new learning
locus coeruleus
motor cortex remains active while most of the brain sleeps; sleepwalkers navigate but are confused and vulnerable
somnambulism (sleepwalking)
awareness of dreaming while asleep; partial frontal and temporal cortex activity allows monitoring and some control
lucid dreaming
