CC6: Sleep Disorders Flashcards
VLPO/MNPO are ventrolateral & median pre-optic areas in hypothalamus. They are sleep centers. They are silent during wakefulness, and fire rigorously during NREM.
Explain the specific role of MNPO & VLPO in sleep.
MNPO –> fires as one drifts into sleep
VLPO –> fires while asleep to maintain sleep; it contains GABA & Galanin which are inhibitory and will project to LC, PAG, LDT/PPT, DR, and Orexins, decreasing the secretions of wakefulness NTs.
Does NREM require GABA and Galanin?
GABA and Galanin will inhibit LC, PAG, LDT/PPT, DR and Orexins from secreting wakefulness NTs, allowing the person to go to NREM sleep. The MNPO/VLPO firing produces the GABA and galanin.
REM sleep is considered “wakefulness while asleep.” What is REM sleep controlled by?
REM sleep is controlled by LDT/PPT nuclei, secreting acetylcholine. ACh not only promotes wakefulness, but it also provides atonia (paralysis) by stimulating neurons in the medulla that release GABA & glycine into spinal motor neuron tracts.
What mediates the changes from stages of NREM & REM?
During NREM, 5-HT, NE, DA all fire to some degree to suppress acetylcholine, allowing the process of sleep staging thru out the night. During REM, acetylcholine peaks & inhibits 5-HT, DA & NE.
What are somnogens?
Somnogens put you to sleep/alter sleep cycle.
Adenosine is a somnogen. We use energy (ATP), which will be broken down into adenosine. Increasing amts of adenosine will have what effect on the wakefulness and sleep centers?
- increasing amts of adenosine will inhibit the wakefulness center
- increasing amts of adenosine will stimulate the VLPO sleep center, releasing GABA & galanin to induce sleepiness
Therefore, sleep is homeostatically driven/regulated.
What is the effect of caffeine on adenosine receptors?
caffeine will antagonize adenosine receptors leading to lower amts of adenosine = less desire to sleep = increased wakefulness.
If there’s no light signal, the suprachiasmic nuclei of hypothalamus will allow the release of melatonin from pineal gland. Therefore, the SCN controls the circadian clock. What genes control the clock?
- “clock genes” & clock proteins control the circadian clock.
- these genes will cause the increased synthesis of proteins. that will inhibit other genes. Ultimately, will convince SCN to synchronize and create a 24 ht clock.
Therefore, the time it takes to transcribe and translate creates the 24 hr clock.
What are some outside factors that that can modify our clock?
- exogenous melatonin
- caffeine (antagonizes adenosine receptors)
- alcohol (CNS depressant)
- light
- food
- exercise/activity
- social interaction
The balance btw ____________ & __________ is important in sleep/wake cycles.
adenosine homeostasis & circadian clock
What is insomnia and how to treat it?
Insomnia is when there’s difficulty initiating or maintaining sleep, early morning awakening, or non-restorative sleep x 1 month.
Sleep deprivation can cause decreased frontal lobe activity, making people prone to errors.
Treat with sleeping pills (increase GABA, blood pressure meds) and sleep hygiene
What is hypersomnia and how to treat it?
Hypersomnia is excessive day time sleepiness and inability to maintain wakefulness.
Treat with stimulants (NE, ACh, 5-HT, Dopamine) & wakefulness hygiene.
What is narcolepsy and how to treat it?
Narcolepsy is when someone experiences daily sleep attacks x 3 months. High emotional states can trigger drop attacks (muscle tone loss), cataplexy/hypnopompic. Patient can also have hyponogogic hallucinations. These patients GO STRAIGHT INTO REM (NO REM LATENCY). Sleep paralysis is common.
Treat with stimulants (NE, ACh, 5-HT, Dopamine), and wakefulness hygiene (nap 20 min every 2 hrs)
There are breathing related sleep disorders that can lead to insomnia or hypersomnia, such as central apnea and obstructive apnea. Compare the two. What are some treatments?
1) central apnea
- brainstem forgets to breathe
2) obstructive apnea
- can’t move air past tissues (could be due to loss of muscle tone)
Treatments include CPAP devises, dental devises. Surgery is not effective, and AVOID SEDATIVES (alcohol, anti-anxiety).
There are circadian rhythm sleep disorders that put our 24 hr circadian clock out of sync. Describe the advanced type and the delayed type of circadian rhythm sleep disorders.
What are some treatments?
1) advanced type (common in elderly)
- fall asleep too early at night, wake up too early in the morning
2) delayed type (jet lag, shift work)
- fall asleep way too late & wake up way too late
*treat with sleep scheduling, melatonin, benzodiazepines, exercise, stimulants or light therapy.
