Sleep inversion

Individuals with the delayed sleep phase type of the disorder exhibit habitually late sleep hours and an inability to change their sleeping schedule consistently. They often show sleepiness during the desired wake period of their days. Their actual phase of sleep is normal. Once they fall asleep, they stay asleep for a normal period of time, albeit a period of time that starts and stops at an abnormally late time.

Sleep inversion may be a symptom of elevated blood ammonia levels^[2] and is often an early symptom of hepatic encephalopathy.^[3] Sleep inversion is a feature of African trypanosomiasis, after which the disease takes its common name, "African sleeping sickness";^[4] sleep-wake cycle disturbances are the most common indication that the disease has reached the stage where infection spreads into the central nervous system.^[5]

• Jet lag
• Shift work sleep disorder
• Circadian rhythm
• Delayed sleep phase disorder
• Encephalitis lethargica
• Lethargy

• Diagnostic and Statistical Manual of Mental Disorders (4th text revised ed.). Washington, DC: American Psychiatric Association. 2000.^{[page needed]}
• Buysse DJ, Morin CM, Reynolds CF (1995). "Sleep Disorders". In Gabbard GO (ed.). Treatments of Psychiatric Disorders (2nd ed.). Washington, DC: American Psychiatric Press.^{[page needed]}
• Hobson JA, Silvestri R (1999). "Sleep and Its Disorders". In Nicholi AM Jr (ed.). The Harvard Guide to Psychiatry. Cambridge, MA: Belknap Press of Harvard University Press.^{[page needed]}
• "Sleep-wake inversion (Concept Id: C0338497)". MedGen. NCBI. NIH. Retrieved 2 August 2024.
• Thorpy MJ, Yager J (2001). The Encyclopedia of Sleep and Sleep Disorders (2nd ed.). New York: Facts on File.^{[page needed]}

• American Sleep Disorders Association