sleep disorders

Question 1

what is the physiological sleep wake cycle

Answer 1

1. 24 hours
   - internal clock resetting by cues
   - melatonin secretion increased during sleep and is suppressed by bright light
   - neurotransmitters (GABA for sleep promoting, NE/DA/Ach/Histamine/Orexin for wakefulness)
2. normal sleep architecture
   - wakefulness
   - non-rapid eye movement sleep for 75% of TST (stage 1 is light sleep, stage 2 is deeper sleep, stage 3 is restorative sleep)
   - rapid eye movement sleep for 25% of TST (memory consolidation, dreaming, sensorimotor development)
   - cyclical (4-6cycles every night, 70-120min every cycle)

Question 2

how would you explain what is insomnia

Answer 2

the inability to initiate or maintain sleep and associated with daytime problems such as fatigue, problems concentrating, and impaired memory etc

Question 3

what is the presentation and diagnostic criteria for insomnia (DSM5)

Answer 3

primary complaint of unsatisfying sleep quantity or quality with presence of at least one of the following
- difficulty with sleep initiation
- difficulty with sleep maintenance
- early morning awakening

also, functional distress or impairment and complaint occurs despite ample opportunities to sleep and occurs for 3nights or more a week and for at least 3m

Question 4

how can insomnia be classified

Answer 4

as a disorder (less common)
- episodic if 1m to <3m
- persistent if 3m or longer
- recurrent if at least 2 episodes within 1 yr

as a symptom
- acute transient (<1w)
- acute short-term (<4w)
- chronic (>4w)

Question 5

what are the likely causes for each classification of insomnia (as a symptom) and their management strategies

Answer 5

acute transient (<1w)
- likely by acute stressors
- manage by sleep hygiene, usually self-limiting

acute short-term (<4w)
- likely by acute stressors
- manage by sleep hygiene and consider short term hypnotic 7-10d (up to 2-4w)

chronic (>4w)
- likely secondary to underlying psychiatric and/or medical problems, poor sleep hygiene, substance abuse, primary sleep disorder (sleep apnea or restless leg syndrome)
- manage by investigating and managing underlying causes, sleep hygiene and discourage long term use of hypnotics

Question 6

what is the non-pharmacological management of insomnia

Answer 6

• CBT-insomnia
• relaxation techniques
• sleep restriction therapy
• stimulation control therapy
• good sleep hygiene

Question 7

how to advice on good sleep hygiene

Answer 7

• avoid caffeine, nicotine or alcohol especially later in the day
• avoid large meals within 2hrs of bed time
• avoid drinking fluids after dinner to prevent frequent night time urination
• only use your bed for sleep, sit on chair if just want to relax
• avoid watching tv in bed
• establish a routine for going to bed
• set aside time to relax before bed and utilise relaxation techniques
• create a conducive environment for sleep (comfortable temperature, earplugs if too noisy, darker room, extra mattress if needed)
• think pleasant thoughts and relax when in bed
• wake up at same time every day including weekends, use an alarm clock if needed
• avoid day time naps but if required, do so before 3pm and total napping time <1hr
• pursue regular physical activities like walking but avoid vigorous exercise too close to bedtime

Question 8

what is the general idea behind pharmacological management of insomnia

Answer 8

*fast-acting anxiolytics, sedatives, hypnotics as adjuncts for short-term relief of distressful insomnia or anxiety

• anxiolytics induces sleep when give at night
• hypnotics sedate when given in the day
• antipsychotics tranquilize without impairing consciousness or causing paradoxical excitement, can be used to calm disturbed patients

hypnotics include BZP, Z-hypnotics, antihistamine, melatonin receptor agonist, orexin receptor antagonist

Question 9

elaborate on BZP (agent, dose, moa, s/e)

Answer 9

agents: lorazepam, diazepam

moa: potentiate GABA, relieve anxiety and insomnia

side effects: sedation, drowsiness, muscle weakness, ataxia, amnesia

dose: lorazapam 0.5-2mg at bedtime PRN, diazepam 2-15mg at bedtime PRN

Question 10

elaborate on z-hypnotics (agents, moa, s/e, dose)

Answer 10

agents: zolpidem, zolpiclone

moa: preferentially binds to benzodiazepine binding sites with gamma and alpha 1 subunit to cause sedation

s/e: taste disturbance with zolpiclone

dose: zolpidem 10mg at bedtime PRN (half dose for females), zolpiclone 7.5mg at bedtime PRN (half dose for elderly)

Question 11

elaborate on antihistamines (agents, moa, s/e, dose)

Answer 11

agents: promethazine, hydroxyzine

moa: H1 antagonism

s/e: anticholinergic (dry mouth, constipation, urinary retention, delirium in elderly), sedation

dose: 25-50mg ON PRN

Question 12

elaborate on melatonin receptor agonist (agent, moa, s/e, dose)

Answer 12

agent: melatonin

moa: MT1 and MT2 agonist

s/e: HA

dose: 2mg 1-2hrs before bedtime after food

Question 13

elaborate on orexin receptor antagonist (agent, moa, s/e, dose)

Answer 13

agent: lemborexant

moa: OX1 and OX2 antagonist

s/e: somnolence, nightmare

dose: 5-10mg at bedtime PRN

c/i in narcolepsy, severe H impairment, moderate to strong 3A inhibitor or inducer