Sleep Disorders

Narcolepsy

Narcolepsy is a neurological disorder that decreases the ability to control the sleep-wake cycle. It is a REM disorder; patients typically enter REM within 10 minutes. It is linked to a deficiency in hypocretin (also known as orexin).

Narcolepsy patients experience 4 main symptoms (narcoleptic tetrad):

• Sleep attacks and excessive daytime sleepiness (most common symptoms)
• Cataplexy (pathognomonic sign): sudden loss of consciousness and symptoms ranging from slurred speech to total body collapse (can be triggered by loud noise, emotions, etc.)
• Hypnopompic and hypnogogic hallucinations (common)
• Sleep paralysis: the inability to move or speak while falling asleep or waking up from sleep

Treatment is modafinil or psychostimulants to treat the sleepiness and an antidepressant to treat the cataplexy.

Sleep Apnea

With sleep apnea, individuals have episodes of apnea during the night causing them to have difficulties breathing. It is characterized by a loud snore and common in obese, middle-aged men.

• Obstructive or upper airway sleep apnea: airway collapses or becomes blocked during sleep
• Central sleep apnea: area of the brain that controls breathing does not send the correct signals to the breathing muscles; often associated with medical problems
• Mixed sleep apnea: patients experience both obstructive and central sleep apnea

Clinical presentation includes:

• High risk of sudden death during sleep
• Development of severe nocturnal hypoxemia
• Pulmonary and systemic hypertension (with elevated diastolic pressure)
• Nocturnal cardiac arrhythmias (potentially life-threatening)
• Bradycardia, then tachycardia

Symptoms commonly include dry mouth, headaches, and daytime tiredness. Restlessness and loud snoring are typically reported by sleep partners.

To diagnose, patients are referred to nocturnal polysomnography or home sleep tests to monitor pulse, oxygen level, etc. Treatment may be limited to diet or smoking cessation (mild cases); CPAP (continued positive airway pressure) in moderate to severe cases; and surgery in cases due to obstructive reasons.

Insomnia

Insomnia is characterized by difficulty initiating and maintaining sleep (DIMS).

• Primary insomnia
• Secondary insomnia (most common) is caused by medical problems, psychiatric problems, medications, etc.

Symptoms of insomnia include sleepiness during the day, general tiredness, irritability, and problems with concentration or memory.

Treatment varies:

• Sleep hygiene
• Behavior modification: stimulus control
• Pharmacotherapy: zaleplon, zolpidem, eszopiclone (work on sleep receptors to help individual to fall and stay asleep)
• Ramelteon, a melatonin receptor-agonist, works on the sleep wake cycle and has less incidence of dependence

Table 8-2. Parasomnias

Diagnosis	Sleep Stage	Features	Treatment	Memory for Event
Night terror	3	Common in young boys Familial Wake up in middle of night and scream	Benzodiazepines	No
Nightmares	REM	Common during stressful times	Antidepressants	Yes
Somnambulism (sleepwalking)	3	Confused and disoriented if awakened Common in children May harm themselves	Benzodiazepines	N/A
Bruxism (teeth grinding)	2	Usually stress-related	Teeth guards	N/A

Recall Question

1. A 25-year-old man is being evaluated for difficulty sleeping by his primary care physician. Upon questioning he states to having excessive daytime sleepiness with sleep attacks and episodes of sudden loss of consciousness. In which of the following neurotransmitters is he most likely deficient?

   1. Serotonin
   2. Acetylcholine
   3. Hypocretin
   4. Norepinephrine
   5. Dopamine

Answer: C