Definition: This condition may result when an individual’s internal biological clock is out of sync with external time cues, including the natural dark-light cycle. This may occur in total blindness, with shift work or jet lag, or due to advanced or delayed sleep phase syndrome. The mismatch may lead to insomnia or hypersomnia at inappropriate times.
Examples: My son is totally blind and he suffers from a circadian rhythm sleep disorder because of this.
