Sleep health + Obstructive sleep apnea

What is a circadian rhythm?

is a biological clock which regulated bodies sleep / wake cycle

what are the factors involved in circadian rhythm

- input
-master clock (Core oscillator)
- output

where is the master clock for circadian rhythm found

can be found in the hypothalamus

what is the main hormone that regulates circadian rhythm and whats its role

as we reach the night cycle melatonin production increases, this is responsible for activating night cycle behaviours

what is the process of circadian rhythm activating wake cycle

- input --> sunlight will be recived by cells in the eye which transmit the message to the master clock
- master clock --> input received by hypothalamus which results in release of neurotransmitters which activate wake cycles
- output --> change of major organ behaviours for wake cycle

What is the homeostatic cycle

energy use will increase the energy debt as our day goes by, this energy debt will reach a max point where our sleep drive is at its highest

whats the link between circadian rhythm and homeostatic cycle

during moring --> energy debt and melatonin should be at its lowest

throughout day --> energy debt and melatonin will increase alongside each other

sleep time --> energy debt and melatonin should be at its highest

what is happening in our brain during awake phase

circadian system and activated clock genes will activate neurons in the brain which fire messages all throughout the brain which help you stay awake and do day activities

this is where sleep urge is at its lowest

whats happening in our brain during sleep phase

GABA neurons will inhibit wakefulness neurons increasing the sleep need and urge

why are orexin neurons important in our sleep cycle

orexin neurons are responsible for seperating our awake and sleep phases, preventing any sudden changes between phases

what can loss of function in orexin neurons cause

loss of function in orexin neurons can cause narcolepsy which is a condition that results in sudden changes in sleep phase, where someone who is awake can suddenly fall asleep

how can age affect sleep cycle

- sleep cycle can be fragmented resulting in frequent wake ups at night
- REM sleep is reduced

what is insomnia

Difficulty in falling asleep or staying asleep

what can cause insomnia

- Circadian process misalignment
- Delayed of advanced melatonin secretion
- Homeostatic process irregularities
- Maladaptive sleep health behaviours
- Over activity in neuronal circuits

what can cause circadian misalignment

when the circadin clock is alterd by factors such as
- light / dark cycles --> working night shifts can result in brain getting confused
- activation of metabolic pathways through late night snacking

your brain wants to activate sleep cycle but factors such as environment or lifestyle are interrupting it

what happens during homeostatic misalignment and how is it caused

homeostatic misalignment is when energy debt and sleep drive is at its max at unusual times

this can be caused as a result of
- poor sleep routine (sleeping to late at night and waking up late)
- poor sleep hygiene (eating late at night, exercising late at night, taking naps and drinking caffeine after mid day)

what are likely causes of delayed sleep phase syndrome

- delayed melatonin production which results in the person sleeping later at night

this is more prevalent in teenagers due to hormonal changes

what are the likley causes of Advanced sleep phase syndrome

- when the melatonin drive occurs to early causing people to sleep earlier

How should insomnia be diagnosed and seen asmaybe examinable

insomnia should always seen as a primary disorder that should always be treated, it should be considered a symptoms of other causes rather should be its own disorder

how can we diagnose someone with chronic insomnia

when a person is experiencing insomnia for more then 3 days a week for 3 months

what are long term issues with acute insomnia

acute insomnia can eventually lead to chronic insomnia, this can be due to the worry and anxiety generated by the person when trying to sleep, resulting in the person not being able to sleep due to overthinking it. This can alter sleep behaviour and result in mental disorders which leads to chronic insomnia.

what is the first line of treatment for insomnia

providing cognitive and behavioural treatments through referral and providing them with sleep hygiene tips

what are some behavioural tips for treating insomnia

Sleep hygiene:
- Go sleep and wake up same time
- No caffeine or alcohol after midday
- Not exercising in the evening
- Avoid napping

Stimulus control:
- If unable to sleep while in bed for 20 mins, get up and do a boring task away from the bed

Cognitive therapy:
- Addressing anxiety

how can benzodiazepines help with insomnia

benzodiazepines help activate GABA receptors in the brain which are responsible for inhibiting wakefulness cycle

what are some practice points for benzodiazepines

- should only be used for short term (2-4 weeks) due to tolerance
- can cause side effects such as blurred vision, dizziness, hangover sedation

how can orexin receptor antagonists drugs help with insomnia

are orexin receptor anatgonists help people stay awake by regulating change between sleep / awake cycles

therefore by disabling it people go into sleep cycle and fall asleep

how can antihistamines (H1 receptor antagonists) be used to help with insomnia

Blocking the H1 histamine receptors (responsible for mediating wakefulness) which as a result makes the person want to sleep

practice points of antihistamines

- should only be used for short term (around 3 days) due to tolerance
- avoid in elderly due to them being more prone to anticholinergic effects and chances of falls
- avoid in children <2 years

how can melatonin be used to help with insomnia

helps increase melatonin drive which will help the person go into sleep phase

what population should melatonin be used in

- elderly due to decreased melatonin drive
- Used in children with neurodevelopmental disorders which have abnormal melatonin's secretion (extended release formulation)
- for people who experience jet lag, night shift work and lifestyle habits that shift circadian rhythm

practice points of melatonin

- Melatonin should be taken around 2 hours before bedtime for optimal effect
- avoid in hepatic impairment

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what is sleep apnoea

temporary cessation of breathing during sleep

what are the two types of sleep apnea

obstructive sleep apnea and central sleep apnea

what is the pathophysiology of sleep apnea

when we go into our sleep phase, the tone in our muscles will relax. Muscles in the upper airway such as tounge and uvula when relaxed are pushed by gravity and form a obstruction in the airways

when the person is not able to breathe the high CO2 levels in the body are detected by receptors which send signals tor the brain that they are not breathing

the body will experience a micro arousal (short period of wakefulness) where the body starts breathing again

what is the difference between central and obstructive sleep apnoea

central --> the problem is associated with function of the body

obstructive --> the issue is the lack of space in upper airways

what are some reasons for obstructive sleep apnoea

Obesity (presence of fat)

Presence of tumour

Infection in airways causing inflammation

what are some reasons for central sleep apnoea

Upper airway muscle control

Miscommunication between lung and brain resulting in poor respiration control

how can we diagnose sleep apnoea

through polysomnography (PSG) test

what does the polysomnography (PSG) test consist of

the PSG test consists of a variety of channels which measure different outcomes such as:
- electroencephalography (EEG),
- electro-oculography (EOG),
- electromyography (EMG),
- pulse oximetry (SpO2),
- electrocardiography (ECG) and
- measurement of respiration and respiratory movements

what are the different type of sleep studies and what do they measure

Type 1 → in lab PSG test which is the diagnostic gold standard which includes 12 channels being measured
Type 2 → a portable home based diagnostic which is acceptable as a diagnostic test (measures at least 7 channels)
Type 3 → measures around4 channels
Type 4 → single channel measurements

what is hypopnoea

when there is a reduction in ventilation by at least 50% which also causes O2 saturation levels to decrease by 4% or more

at which stage of sleep does apnoea usually occur

during REM sleep since the tone of muscles decreases during this time

what do we use to categorise obstructive sleep apnoea

apnoea- hypopnea index

what is the apnoea- hypopnea index equastion

AHI = no. of apneas + hypopneas / total sleep time in hours

what categories of apnoea- hypopnea index are there for obstructive sleep apnoea

AHI values <5 --> normal
AHI values 5-14 --> mild
AHI values 15-29 --> moderate
AHI values 30> --> severe

when a person experiences sleep apnoea what happens in the body

Increased heart rate → due to low O2 levels the heart pumps harder so more oxygen reaches each organ

Hyperventilation

Increased glucose levels → release of glucose so the body has energy to increase heart rate

what are some health consequences associated with frequent sleep apnea

- insulin resistance (due to constant release of glucose during sleep to provide energy for heart rate)
- hypertension --> increased heart rate
- cardiomyopathy
- heart failure
- stroke
- pulmonary hypertension
- depression
- glucose intolerance

what are symptoms of obstructive sleep apnoea

- Loud snoring
- Daytime sleepiness'
- Poor sleep quality
- Morning headache
- ↓libido
- Nocturia
-↓memory concentration

what are some risk factors of obstructive sleep apnoea

- males
- obesity
- smoking
- age
- alcohol

to what patients is the CPAP machine gold standard treatment for

CPAP machine is gold standard treatment for patients with moderate to severe obstructive sleep apnoea

for a patient with mild to moderate obstructive sleep apnoea what is the typical treatments

Mandibular advancement splints (MAS) and nasal EPAP (not much evidence)

what types of surgeries are availbe for people with obstructive sleep apnoea

bariatric surgery --> for really obese patients, heling them lose weight

upper airway surgery --> suitable for most OSA patients

tonsillectomy --> useful for children, helping with large tonsils

what are some lifestyle managements of OSA

losing weight, stopping smoking and alcohol

what is CPAP

continuous positive airway pressure -- a means of continuously blowing positive air into the airway to prevent airway collapse or to help alleviate difficulty breathing

gold standard for OSA in moderate to severe cases

what equipment is found in a CPAP

the CPAP consists of a machine which sucks in room air and pressurises it for inhalation

humidifiers are also present to prevent cold dry air from reaching the lungs

the pressurised air can then travel through tubing and into a mask worn by the patient

what are some types of CPAP machines

- auto set algorithm --> smart machine that detects when apnea occurs and measures how many times it occurs

- manual titration --> manually choosing the pressure at which the machine will produce to keep airways open

what are some problems with CPAP machines

Adherence

Side effects- nasal dryness, dry mouth, pressure sores, infections

Social/lifestyle, attitude

Expense

Psychological- claustrophobia

how can patients care for CPAP

Tubing inspection

Mask care, new masks

Filters

Machines

what is the PALM model

a model which consists of 4 variables which are measured in an individual.

these variable can differ between patients which expresses different types of phenotypes

what is the P in the PALM model

Pcrit → is the critical pharyngeal pressure, which determines at what pressure causes the airways to close (the pressure at which closes the airways will differ between patients)

what is the best treatment for patients with a high pcrit value (phenotype)

since the pharyngeal collapse is the main problem the CPAP machine is most effective

what is the M in PALM model

muscle responsiveness --> the muscles which hold the airways open are not functioning well

what is the best treatment for patients with low muscle responsiveness (phenotype)

a way to stimulate the muscles

what is the L in PALM model

Loop Gain --> the bodies reaction to a change in the respiratory system (e.g., amount of oxygen in the body)

having a high loop gain means that the body overexaggerates to the smallest changes in the respiratory system

causing them to wake up to easily

the ventilatory response (waking up and increasing breathing) is to much for the ventilatory changes (decreased ventilation, obstruction) that have occurred in the body

what is the A in PALM model

Arousal --> where very small changes in a persons body causes them to wake up

easily woken up

what are some pharmalogical treatments for patients with low arousal threshold (phenotypes)

sedatives

what are some pharma logical treatments for patients with unstable loop gain (phenotype)

Carbonic Anhydrase Inhibitors e.g.
acetazolamide

what are some pharma logical treatments for patients with upper airway collapsibility (phenotype)

Desimipramine (TCA)
Fluticasone, Leukotriene Receptor Antagonists

REM Sleep (antidepressants, clonidine)

Muscarinic tone to reduce REM based UA muscle inactivation e.g. donepzil

Cannabinoids CB1 and CB2 receptor agonists