💊 Orexin System Narcolepsy-Insomnia Spectrum Simulator

Narcolepsy: Orexin Neuron Loss and Sleep Intrusion

Severe orexin neuron loss lets sleep invade wakefulness.

• ~90%: Orexin neurons lost (in narcolepsy type 1)
• <110 pg/mL: CSF orexin-A level (diagnostic threshold)
• ~70%: Cataplexy prevalence (of type 1 cases)
• <15 min: Sleep-onset REM (abnormally fast REM entry)

Autoimmune neuron destruction

Immune cells attack hypothalamic orexin neurons directly.

Cataplexy and emotional triggers

Strong emotions trigger sudden muscle weakness episodes.

Fragmented nighttime sleep

Lost orexin destabilizes sleep-wake switching constantly.

Mild Orexin Reduction and Daytime Sleepiness

Modest orexin decline brings mild daytime drowsiness.

• 60–90%: Orexin tone (of normal baseline)
• 10–14: Epworth sleepiness score (mild-moderate elevation)
• Occasional: Microsleep frequency (brief attention lapses)
• Near normal: Nighttime sleep quality (mostly intact continuity)

Subclinical arousal weakening

Wake drive weakens without full narcoleptic symptoms.

Afternoon sleepiness dips

Sleepiness peaks during the natural afternoon circadian dip.

Compensated arousal networks

Other arousal systems partly compensate for the loss.

Balanced Arousal and Healthy Sleep-Wake Cycling

Balanced orexin signaling supports stable, healthy alertness.

• 100%: Orexin tone (reference baseline)
• >90%: Sleep efficiency (time asleep in bed)
• 10–20 min: Sleep latency (normal sleep onset)
• Stable: Daytime alertness (consistent energy all day)

Circadian-orexin coordination

Orexin neurons fire rhythmically with the circadian clock.

Flexible sleep-wake switching

Healthy orexin allows quick, clean state transitions.

Homeostatic pressure balance

Sleep pressure and arousal drive stay well matched.

Excess Arousal Drive and Sleep Resistance

Excess orexin signaling makes falling asleep genuinely hard.

• 130–160%: Orexin tone (above normal baseline)
• >30 min: Sleep latency (delayed sleep onset)
• Elevated: Cortical arousal (heightened wake signaling)
• Increased: Stress hormone coupling (orexin-cortisol crosstalk rises)

Hyperactive wake-promoting neurons

Orexin neurons fire excessively, resisting sleep onset.

Stress and orexin feedback

Chronic stress further amplifies orexin neuron activity.

Delayed sleep initiation

Racing arousal circuits keep the brain wired awake.

Chronic Hyperarousal and Sleep-Onset Insomnia

Persistent hyperarousal locks the brain in wakefulness mode.

• 170–200%: Orexin tone (sustained excess signaling)
• ~10%: Chronic insomnia prevalence (of adults affected)
• >45 min: Sleep latency (severe onset delay)
• OX1R/OX2R: Suvorexant target (dual antagonist mechanism)

Dual orexin receptor blockade

Dual antagonists dampen excess orexin receptor signaling.

Cognitive hyperarousal loop

Racing thoughts and elevated orexin reinforce each other.

Treatment target rationale

Restoring balanced orexin tone is the treatment goal.