It has also been used to correct the insomnia associated with delayed sleep phase disorder.

Some night owls who have great difficulty adopting normal sleeping and waking times may have delayed sleep phase disorder.

Delayed sleep phase disorder can be misdiagnosed as insomnia as it causes a delayed period of sleep, spilling over into daylight hours.

When used several hours before sleep, it magnifies the clock resetting effect of light at wake-up, which is particularly useful for normalizing the sleep pattern in patients with delayed sleep phase disorder.

As with delayed sleep phase disorder (DSPS or DSPD), in the absence of neurological damage due to trauma or stroke, cases almost never appear after the age of 30.

Chronic circadian rhythm disorders, the most common of which is delayed sleep phase disorder, may be managed by specifically timed bright light therapy, timed oral administration of the hormone melatonin, and/or chronotherapy.

According to Miran, there is evidence that melatonin eases circadian rhythm disorders like jet lag and delayed sleep phase disorders, but it hasn't been proven effective in treating insomnia or improving sleep quality.

People with DSPS (Delayed sleep phase disorder), more common than Non-24, do entrain to nature's 24 hours, but are unable to sleep and awaken at socially preferred times, sleeping instead, for example, from 4 a.m. to noon.

Delayed sleep phase disorder (DSPD), aka delayed sleep phase syndrome (DSPS), characterized by a much later than normal timing of sleep onset and offset and a period of peak alertness in the middle of the night.

For example, upper airway resistance syndrome and delayed sleep phase disorder were formerly confused with idiopathic hypersomnia, but now that they have been more clearly defined, one can more carefully exclude these causes of EDS in order to more correctly diagnose idiopathic hypersomnia.

An American Academy of Sleep Medicine Review: Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep-Wake Rhythm.