Sleep Flashcards
What are the two main processes of sleep-wake regulation?
- Circadian Process C: internal clock
2. Homeostatic Process S: sleep pressure
What are the major nuclei of the hypothalamus involved in sleep-wake regulation?
suprachiasmatic nucleus and ventrolateral preoptic area
What area of the pons is involved in the regulation of sleep-wake cycle?
the ascending reticular activating system
What is the human circadian rhythm generator and to where is it localized?
the internal clock that has been localized to the suprachiasmatic nucleus (SCN)
When does the output of the SCN peak?
Through the end of a major sleep period and into the middle of the subsequent wake period in each 24 hour cycle.
when is the minimum output from the SCN?
as the wake period ends and sleep begins
What is the crucial role of the SCN circadian rhythm generator?
What process is it associated with?
maintain wakefulness
It is associated with process C
How does light promote wakefulness?
Light hits the retinal ganglion cells that contain melanopsin. The ganglion cell depolarizes and tranduces its signal which travels along the retinalthalamic tract to the SCN of the anterior hypothalamus.
The SCN projects to the PVN which projects to the sympathetic pathway to cervical ganglion.
The postsynaptic of the cervical ganglion regulates the pineal gland which releases melatonin.
Which process drives the homeostatic drive to sleep?
Process S
When is S at at minimum?
It is at a minimum when we have had enough sleep. It increases over the course of the day as we get sleepier. It decreases while we are sleeping.
If you stay up too late, what happens to Process S? What happens to slow waves?
It is highly increases, because you want to sleep. There are increased slow wave activity and longer sleep the next day.
Who demonstrates more significant slow wave response after sleep deprivation?
young people are more affected by sleep deprivation
What does sleep deprivation show on the graph of visual task test?
There is huge standard deviation between people on the effects of sleep deprivation, but overall, sleep deprivation delays response time to visual tasks.
What are the five major stages of sleep?
1-2 are light sleep, 3-4 are deep sleep, and 5 is REM sleep.
What is REM sleep?
transitional step between sleep and wakefulness. It is characterized by rapid eye movements on the EOG
What is the posterior dominant rhythm?
8-12 Hz called the alpha rhythm which is normal brain activity with the eyes closed
What is alpha rhythm?
the normal brain eelctrical activity of an adult when the eyes are closed
What are the two overarching categories of sleep?
REM- rapid eye movement
NREM- non-rapid eye movement
What is the test to record human sleep?
polysomnography
Which sleep stage is more crucial for performance of mental tasks, REM or NREM?
NREM
What three recordings are taken when recording someones sleep cycle?
EEG- occipital and central scalp
EOG- extraocular eye movement
EMG- chin muscle movement
There are two kinds of REM. What are they and what are they characterized by?
Tonic REM- no eye movement
Phasic REM- eye movement
What does the EEG pattern most closely resemble when the person is in REM sleep?
Is the amplitude of spikes high or low?
What is the frequency?
What does this suggest about cerebral activity?
Awake
low amplitude waves
frequency in the alpha (8-12Hz) or beta (13-20Hz) range
This suggests that the cerebral cortex is active with desynchronized neuronal activity
How do you distinguish REM from Awake on the EEG?
Look at the EOG lines to identify rapid eye movement and look at the EMG to see if there is low amplitude chin activity
what percent of a nights sleep is REM?
20-25% ( the second 3-4 hours of the nights rest)
What is the main difference between REM and NREM activity on the EEG?
REM is not synchronized
NREM has synchronized EEG activity
What part of the sleep cycle is associated with synchronized EEG recordings?
What does the waveform look like?
What frequency are the waves in this stage?
NREM sleep has lower frequency, higher amplitude waves
The frequency will be in the theta (4-7Hz) and delta (1-3Hz range)
What are the different wave frequency ranges from lowest to highest?
delta (1-3 Hz)
theta (4-7 Hz)
Alpha (8-12 Hz)
Beta (13-20 Hz)
What four stages was NREM sleep formerly divided into?
1-2 light sleep
3-4 deep sleep
Currently what three stages are NREM sleep divided into?
N1- transitional stage
N2- cessation of conscious stimuli
N3- slow wave sleep
What are the characteristics of N1 stage of sleep? What do you see on the EEG?
it is the transitional stage where you feel yourself getting sleepy
EEG - replaces alpha waves with irregular theta waves. Vertex sharp transients occur sporadically
EOG- slow rolling of eyes
EMG- reduced chin movement amplitude from wake
What stage of sleep is most important for restoration, survival funcitons, mental tasks, conservation of the days memories, regenerate cells from the previous day?
N3- slow wave sleep