Sleep inversion

Sleep inversion or sleep-wake inversion is a reversal of sleeping tendencies. Individuals experiencing sleep-wake inversion exchange diurnal habits for nocturnal habits, meaning they are active at night and sleep during the day. Sleep-wake inversion is an individual symptom, not a condition by itself. It can be due to many reasons, with the main two being circadian rhythm disorders and encephalopathies.

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. The sleep phase cycles may or may not be impaired depending on the causative issue.^[1][2] For example, synucleinopathies such as MSA are known for causing REM issues alongside other sleep impairments.^[3]

Severe cases of delayed sleep phase disorder (DSPD), jet-lag, or other circadian rhythm disorders are non-encephalopathic causes of inverted behaviors. For example, in very severe DSPD, a patient may only feel sleepy right after sunrise and having a waking time late in the day that renders them completely awake for the resulting night. Another more common example is those with jet-lag whose circadian rhythms are not entrained to the destination they have arrived it, which depending on the differences between the time zones of the original location of the traveler and the destination, may cause a temporary reversal of the rhythm until the body can adjust.

Encephalopathic causes are wide and varied, but the most prominent example is African trypanosomiasis in those who end up developing CNS involvement.^[4]

Virtually any encephalitis or neurological issue can cause sleep problems that can emulate circadian rhythm issues, which by extension include sleep inversion.^[1][2]

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

• 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