Lesser-Known Sleep Disorders

Hidden Facets of Sleep

Introduction

• Lesser-known sleep disorders are conditions that are rare or often missed, but clinically important.
• They occur due to disturbance in sleep stages, sleep–wake transitions, or body clock (circadian rhythm).
• Understanding which sleep phase is affected helps in diagnosis and management.

1. Parasomnias (Abnormal Behaviours During Sleep)

• Occur when the brain is partially awake and partially asleep, leading to automatic behaviours without awareness.
• Mostly seen in deep NREM sleep (Stage N3).

Sleep-Related Eating Disorder (SRED)

• Eating during sleep with no memory, due to incomplete awakening from deep sleep.
• Managed by stabilizing sleep, reducing stress, and ensuring safety.

Sleep-Related Behaviour Disorders

• Includes automatic activities like walking or talking during sleep.
• Caused by failure of smooth transition from deep sleep to wakefulness.
• Management focuses on sleep regularity and safety precautions.

Bruxism (Teeth Grinding)

• Occurs in light sleep (N1, N2) due to micro-arousals (brief partial awakenings).
• Leads to jaw pain and tooth damage.
• Managed with stress reduction and mouth guards.

2. Sleep-Related Breathing Disorders

• We have already studied sleep apnea (breathing stops repeatedly).
• Here, we focus on hypoventilation (breathing becomes too slow/shallow).

Sleep-Related Hypoventilation Disorder

• Leads to low oxygen and high carbon dioxide levels during sleep.
• Worse in REM sleep, where breathing muscles are naturally relaxed.
• Causes include obesity, lung disease, brain dysfunction, and sedatives.
• Managed using BiPAP support, treating underlying cause, and avoiding sedatives.

3. Circadian Rhythm Sleep Disorders

• Problem is with timing of sleep, not sleep stages.
• Caused by disturbance in body clock (suprachiasmatic nucleus) and melatonin rhythm.

Non-24-Hour Sleep-Wake Disorder

• Sleep time keeps shifting daily due to lack of proper light signals.

Irregular Sleep-Wake Rhythm Disorder

• Sleep is broken into multiple short periods instead of one continuous sleep.
• Managed with strict routine, light exposure, and limiting naps.

4. REM Sleep-Related Disorders

Sleep Paralysis

• Person is awake but unable to move, due to persistence of REM muscle paralysis (atonia).
• Occurs when REM sleep overlaps with wakefulness.
• May cause hallucinations and fear.
• Managed by improving sleep schedule and reducing stress.

5. Sleep-Related Movement Disorders

Hypnic Jerks

• Sudden jerks at sleep onset (N1 stage) due to unstable sleep transition.
• Common triggers: fatigue, caffeine, stress.
• Managed by relaxation and sleep hygiene.

PLMD (Covered Earlier)

• Repetitive limb movements causing disturbed sleep continuity.

6. Neurological Sleep Disorders

Kleine-Levin Syndrome (Covered Earlier)

• Episodic excessive sleep and behavioural changes.

Fatal Familial Insomnia (FFI)

• Progressive condition where the brain loses ability to produce normal sleep.
• Caused by prions (abnormal proteins) damaging the thalamus (sleep control center).
• Leads to loss of deep sleep and REM sleep, cognitive decline, and systemic dysfunction.
• Managed with supportive care and symptom control.

Final Clinical Understanding

• NREM disorders → abnormal behaviours (partial awakening)
• REM disorders → paralysis and dream overlap
• Movement disorders → unstable sleep transitions
• Breathing disorders → worsen in REM due to muscle relaxation
• Circadian disorders → timing problem, not structure

Always think:
• Which sleep stage is affected?
• How is the brain failing to regulate that stage?

Clinical Approach:
It is crucial to target the psycho-neuro-endocrine and immune systems and assess the emotional state to fix the imbalance.