Final - Sleep Flashcards
What is the most important nucleus in the brain that controls circadian rhythms?
Suprachiasmatic nucleus
(SCN)
Delta Wave Characteristics
High amplitude, low frequency
Type of waves found in SWS?
Delta Waves
In an average night of sleep, what decreases and what increases?
SWS decreases as night progresses and REM sleep increases as the night progresses.
PGO Waves
Originate in the pons and are the first sign of a bout of REM sleep in animals.
Duration of basic rest activity cycle?
Rhythmical patterns approximate 90 minutes
Genes that control Circadian rhythms
- Role
- Location
Period, Time and Clock
- Control circadian rhythms and the intracellular ticking of the cells located in the SCN
What midbrain nucleus is responsible for the production of NE?
Locus cereleus
Zeitgeber
A stimulus (usually the light of dawn) that resets the biological clock and the circadian rhythms.
Where is the SCN of the lateral hypothalamus located?
Directly on top of the optic chiasm.
Sleep Brain Wave States
(Image)
Overview
Sleep Cytoarchitecutre
(Image)
What happens to SWS and REM as the night progresses?
- Stages 3 and 4 (SWS) decrease in frequency and REM periods get longer and more frequent (sometimes taking the place of SWS).
What causes wakefulness at the end of a sleep cycle?
Release of norepinephrine from the locus coeruleus.
Sleep Brain Wave States
(Verbal Description)
- Alpha - Fast and high
- Theta - More rhythmical
- Delta (SWS) - Large amplitude, low frequency
What controls brain wave states?
Release of NTs
- Primary NT impacting brain wave states = norepinephrine. Release or inhibition of NE makes brain wave states active or inactive.
What is Sleep?
You must have a brain and brain wave states to sleep.
Sleep is a behavior and is not the same as quiescence.
Suprachiasmatic Nucleus of the Lateral Hypothalamus
- Role
Nucleus in brain that controls sleep.
Hypothalamus
(Image)
Located below the Thalamus.
Hypothalamus
(Functions)
The hypothalamus controls the drive states.
Fighting, fleeing, feeding, sex (+ sleep)
Reasons for Sleep
- Repair tissues
- Consolidate memories
- Restore brain’s neurochemicals
- Cool the brain
Why are tissues repaired during sleep?
During SWS, you release growth hormones (GHs).
GH keeps the process of cell replication going (all cells, except neurons, are constantly being replicated).
Repair of Tissues:
What happens to SWS & GHs as you age?
As you age, your levels of growth hormon and SWS decrease.
Components of Memory Consolidation
- Getting rid of useless stuff
- Storing new stuff
What happens when you wake someone up from REM sleep?
They’re likely to return to a deeper state of sleep. It’s rare to just fall into REM sleep. After deep sleep, they will progressively return to REM faster.
College Students & REM Sleep
Memory consolidation
College students have more REM sleep during exams (during a period of intense learning, REM sleep increases).
Sleep & Restoration of Brain’s Neurochemicals
Neurons need glucose for energy. During sleep, neurons restore glucose, NTs and enzymes.
Sleep & “Cooling the Brain”
STUPID HYPOTHESIS.
It has been shown that when you go to sleep, your brain temperature falls 1 degree. This doesn’t however explain WHY we sleep.
Brain cools b/c of circadian rhythms of SWS (less activity = neurons fire less = cools/slows entire body temperature).
Temperature of the Body: When is it at its lowest and highest?
Lowest = 3-4am
Highest = 3-4pm
Zeitgeber
“Time-Giver”
Circadian rhythms can be reset by getting light into the retinas. Special retinal ganglion cells absorb light and send a signal to the SCN.
Suprachiasmatic Nucleus
(Picture)
What does the SCN Control?
- Locus coeruleus and its ability to release NE
- Pineal gland
Can blind people have circadian rhythms?
YES
If injury is to V1 and they still have retinal ganglion cells with rhodopsin, they can have normal circadian rhythms.
What NT do the retinal ganglion cells release onto the SCN?
Glutamate.
How Do We Know Circadian Rhythms Are Controlled by the SCN?
- If it’s taken out, there will be an absence of circadian rhythms.
- Blocking glutamate can block circadian rhythms
Ticking
Neurons have time functions called “ticking.”
3 Genes That Allow a Neuron to Tell Time
- Period (“Per”)
- Time (“Tim”)
- Clock (“Clk”)
Basic Rest Activity Cycle (BRAC)
A basic larger rhythm.
Approximately 90 minutes and is active all 24 hours.
Every 90 minutes, you will be in your highest brain wave state/lowest brain wave state.
3 Types of Life Rhythms
- Circadian (~25 hours)
- Biorhythms (longer; e.g., puberty)
- Lifespan (definite lifespan)
Death and the SCN
SCN keeps track of the timing of life. As we age, we get less SWS and release less GH (which programs death b/c we’re no longer replacing cells in our body).
DHEA
Precursor to GH
GHB
Increases the amount of GABA (agonist) in brain and when go to sleep at night, spend more time in SWS (and therefore release more GH).
***Body Builders***
Disruption of Circadian Rhythms & Seasonal Affective Disorder (SAD)
Abnormality of circadian rhythms.
Light therapy stops the release of melatonin.
Schizophrenia & REM Sleep
SZs have less REM sleep and don’t dream as much.
How many cycles of sleep should be completed each night to maintain the health of the brain?
5 complete cycles (need the last and longest REM period)
What % of Americans Have a Sleep Disorder?
50%
How long does it take a sleeping pattern to develop?
In as little as 3 days
Brain Wave States During Wakefulness?
Alpha & Beta
Stage 1 Sleep Brain Wave States
Theta activity. Neuron firing more synchronized.
Stage 2 Sleep Brain Wave States
Theta activity, sleep spindles and K complexes.
SWS
Stages 3+4
Delta Activity
Pineal Gland
Produces melatonin and plays a role in circadian and seasonal rhythms.
Melatonin
Released by pineal gland and helps KEEP asleep
