Sleep cycle & insomnia Flashcards
(33 cards)
Define the term sleep regulation
Where different brain structures are responsible for controlling and regulating sleep & wakefulness.
Inhibition of arousal and sleep-promoting centres affects sleep
We flip between sleep and wakefulness these are influenced by internal & external factors
What neurotransmitters are released during from arousal centre?
Histamine. orexin & acetylcholine
All excitatory neurotransmitters
Where is the arousal Centre located?
This area is found in the hypothalamus and stimulates the cerebral cortex which causes the release of neurotransmitters
Where is the sleep promoting centre found?
This is found in the VLPO
Ventrolateral preoptic nucleus found in the hypothalamus
VLPO produces GABA & galanin which are inhibitory neurotransmitters. Inhibit the wake cycle, causes the arousal centre to shut down and prompts NREM sleep
Describe the meaning of the ‘sleep switch’
It refers to the inhibition made by both neurotransmitters in different cycles, to promote sleep & wakefulness
E.g., when the cerebral cortex is stimulated histamine is released which inhibts the VLPO
What are the 2 components of the sleep wake cycle proposed by borbely?
Process C: circadian rhythm
Process S: body’ internal timer
These processes affect the duration, timing and structure of sleep
Describe process C
SCN communicates the CR to the body by stimulating melatonin production from the pineal gland, melatonin production peaks at night
Melatonin DOES NOT induce sleep, but starts the sleep process
CR controls: level of alertness, sleep tendencies, melatonin, hormone production, cardio/resp function & glucose levels
Describe process S
This is a homeostatic mechanism that counts how long we have been awake/asleep for
As the day goes on a sleep pressure build whilst we are awake
As you sleep the sleep pressure decreases & likelihood of waking increases
Define sleep pressure
The accumulation of adenosine in the cerebral spinal fluid whilst we are awake. Adenosine is released from ATP during R/s from glycogen
Adenosine drops during the night as glycogen stores are replenished
What are the effects of stimulants on sleep e.g., caffeine?
Stimulants act as adenosine receptor antagonists, adenosine is inhibited but levels continue to rise. prevents adenosine from inducing sleep
List external factors that affect sleep (give at least 5 examples)
-Light
- Medication
- medical conditions
- Caffeine
- Alcohol
- Drugs
How does the presence of light effect sleep
Light affects the SCN which is responsible for regulating circadian rhythms. Light stimulates photosensitive areas in the retina which signal the SCN via retinohypothalamic tract. Light exposure therefore directly affects sleep as it is able to reset the body clock
How can medical conditions affect sleep?
Some medical conditions may cause pain which causes difficulty sleeping, also affecting the quality of sleep (depth & length)
Mental disorders e.g., depression can create a sleep delay & reduce quality of sleep, increase in REM sleep
Define insomnia
This is defined as difficulty getting to sleep, staying asleep & waking up earlier than intended to.
15% of adults suffer from chronic insomnia
40% of adults will suffer from insomnia
Insomnia can be induced by lifestyle factors e.g., alcohol & medication
Insomnia is linked to increased risk of depression, heart disease & stroke
How can medications affect sleep?
E.g., Beta blockers can reduce NREM & REM sleep. This can increase daytime sleepiness
Some antidepressants may cause insomnia
Some medication contains caffeine which acts as a adenosine receptor antagonist
What is the effect of alcohol on sleep?
Alcohol may cause us to drift off easier to sleep, but the overall quality of sleep is reduced. You are more likely to suffer with broken sleep
Name daytime symptoms of insomnia (give min 5)
- Lack of concentration
- Irritability
- Accident prone
- Daytime sleepiness
- Depression
- Forgetfulness
- Lack of energy
- Decreased performance in tasks
What are the 4 types of insomnia
- Chronic insomnia
- short-term insomnia
- other insomnia
- normal variants & isolated symptoms
Describe and explain chronic insomnia
Chronic insomnia diagnosis is given when insomnia has occurred minimum 3 times a week for more than 3 months.
This can be further broken down into 3 catergories of paradoxical insomnia, idiopathic insomnia & psychological insomnia
symptoms include:
- accident prone
- irritability
- lack of attention/ concentration
- difficulty maintaining & initiating sleep
- daytime sleepiness
Define psychological insomnia
A form of chronic insomnia in which it is a learned response. A person is unable to sleep when they plan to, difficulty getting to sleep or napping. Can sleep when it is unplanned, this creates anxiety for a person of when & where they will fall asleep next. Creating a vicious cycle of wanting sleep, but not getting it
Define idiopathic insomnia
A form of chronic insomnia in which is detrimental to health. It is lifelong insomnia. It appears in infancy & childhood, no known cause or cure
Define paradoxical insomnia
A form of chronic insomnia in which there is a lack of evidence. Patients will complain of restlessness & fatigue, however there EEG shows evidence of restful sleep
A sleep diary is recommended to keep an eye on sleep habits & hygiene
Define short-term insomia
This is where an individual suffers with insomnia episodes for less than 3 months. A change to lifestyle or a stressful event normally causes it. e.g., a new baby, the death of a friend/family member, or a career change.
This type of insomnia is normally resolved once problem or new lifestyle is adapted to.
Define other insomnia
This is a form of insomnia that does not fit into other categories. Patients may have some aspects of the disorder, but do not show all the symptoms and therefore a proper diagnosis is not given as they do not reach full criteria for short-term or chronic insomnia
