Ultradian Rhythms - Sleep Stages REM/NREM Flashcards
What are the 2 categories of sleep?
REM - rapid eye movement
NREM - non-rapid eye movement
they are biological ultradian rhythms that are shorter than 24 hours
What is NREM sleep?
we enter NREM after falling asleep
consists of 4 sleep stages and takes up 80% of sleep time overall
What are the NREM stage 1 characteristics?
When falling asleep we enter a relaxed state known as a ‘hypnogogic state’
the lightest sleep stage and can be easily awoken
During hypnogogic states we can experience hallucinatory images, such as flashes of light, vivid images, and hypnic jerks
Stage 1 NREM sleep lasts around 5 -10 minutes
What are the NREM stage 2 characteristics?
the point at which “true” sleep begins
last around 20 minutes and can still be easily awoken from
further into stage 2 our eyes stop rolling, muscles relax more, and our breathing and heart rate continue to decrease
Stage 2 sleep accounts for about 50% of our total sleep
What are the NREM stage 3 characteristics?
Stage 3 is brief and is the start of deep sleep
During stage 3 its harder to be awoken and we are less responsive to external stimuli
our eyes don’t move, muscles are relaxed and heart and breathing rates continue to become slower and more regular
What are the NREM stage 4 characteristics?
Stage 4 is the deepest sleep and is really hard to be awoken from
our level of conscious awareness is very low, but we can still be sensitive to certain stimuli (smoke alarm/baby crying)
In the first NREM/REM sleep cycle, we spend about 30 minutes in stage 4
How do sleep patterns work ?
1 cycle consists of NREM stages 1/2/3/4 and then back to 2/3 and skipping 1, REM sleep then begins
our sleep cycle isn’t linear and lasts around 90 mins
once we’ve reached stage 4 we don’t stay in it
What is REM sleep?
a lighter sleep stage than NREM stages 3 and 4, so it’s easier to wake from
ppl are more likely to report dreaming when woken from REM
The first REM cycle lasts around 10 minutes
What physiological changes happen during REM?
Repetitive bursts of rapid eye movement
Heart rate, blood pressure and respiration increase and fluctuate
Body temperature matches surrounding environment
Genitals are aroused
NO muscle tension (known as muscle atonia or cataplexy)
Why is REM considered a paradoxical sleep?
Because bodies appear normal externally, but the bodily systems are highly active
REM brainwaves appear similar to NWC on EEG machines
When does dreaming occur during sleeping?
occurs during REM sleep mostly
When does dreaming occur during sleeping?
Dreams appear mostly during REM sleep
Final dreams of the night are often the longest, bizzare and most memorable
Anxious or lighter sleeping people are also more likely to dream during NREM
What are hypnograms?
Graphs that display data of a persons sleep cycle
