In sighted individuals: Daily exposure to the light-dark cycle synchronizes the circadian clock with the 24-hour day.1,2
SCN, suprachiasmatic nucleus.
The SCN controls daily circadian rhythms, including the production of melatonin and cortisol, as well as body temperature. Lack of synchronization of the SCN results in the misalignment of these circadian rhythms, including the sleep-wake cycle, which can differ between individuals.3
In most people who are totally blind: Without light perception, sleep-wake cycles shift, often becoming dyssynchronized with the 24-hour day.1
Lack of light perception can lead to the dyssynchronization of the endogenous circadian clock with the 24-hour light-dark cycle2
References: 1. Lockley SW, et al. In: Kushida C, ed. The Encyclopedia of Sleep. Vol 3. Waltham, MA: Elsevier; 2013:34-40. 2. American Academy of Sleep Medicine. International Classification of Sleep Disorders. 3rd ed. Darien, IL: American Academy of Sleep Medicine; 2014. 3. Sack RL, et al. J Clin Endocrinol Metab. 1992;75(1):127-134.
The most common adverse reactions (incidence >5% and at least twice as high on HETLIOZ® (tasimelteon) than on placebo) were headache, increased alanine aminotransferase, nightmares or unusual dreams, and upper respiratory or urinary tract infection. The risk of adverse reactions may be greater in elderly (>65 years) patients than younger patients because exposure to HETLIOZ® is increased by approximately 2-fold compared with younger patients.
HETLIOZ® is indicated for the treatment of Non-24-Hour Sleep-Wake Disorder (Non-24).
Please see full US Prescribing Information.