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Familial delayed sleep-phase syndrome

The Familial Advanced/Delayed Sleep-Phase Syndrome (FASPS/FDSPS) is an inherited disorder in the circadian rhythm of sleep which affects the rhythm of the core body temperature, the individual´s attention span, hormonal and other “”normal”” biological rhythms compared to those of social standards and the general population.

Those individuals affected by FASPS consistently go to sleep very early and are very early to rise. It was the first human, mendelian circadian rhythm variant to be well-characterized, and was shown to result from a mutation in a phosphorylation site within the casein kinase I (CKI)-binding domain of the human PER2 gene.

Patients with Familial Delayed Sleep-Phase Syndrome (FDSPS) frequently say that they cannot sleep until early dawn hours, nonetheless they fall asleep at the same time every day unless they have some other sleep disorder besides FDSPS. They sleep the number of hours perfectly, the same as those persons without the disorder. However, it is very difficult for them to wake up to go to work or school; they have their own schedules (eg., 4:00 am – noon), sleep deeply, wake spontaneously and do not feel fatigue or sleepiness during the day.

This syndrome was discovered by Dr. Elliot D. Weitzman and his team at the Montefiore Medical Center and this health problem explains the 8 – 12% of the chronic insomnia complaints. Nonetheless, individuals with FDSPS do not receive the appropriate treatment or even treatment at all. FDSPS is misdiagnosed as primary insomnia of a psychiatric disorder.

The disorder generally develops in childhood or adolescence and when it develops in adolescence, can disappear in early adulthood. Otherwise, it is a life-long disorder.

Depending on the severity of the syndrome, the symptoms can be controlled to a lesser or greater degree, but there is no specific cure. It is equally distributed between men and women and has been linked to an attention deficit disorder (ADD) since the gene polymorphism found in ADD patients and their circadian rhythms are common in a high proportion with FDSPS patients.


Treatment for FDSPS is specific and different from the treatment for insomnia and should take into account the ability of the patient to sleep well while treating the problem.

Light cases of FDSPS can be controlled by simply trying to change the time of going to bed each day by 15 minute increments, until the desired scheduled is reached. Chronophototherapy, consisting of initializing the circadian clock by going to bed several hours “”earlier”” or “”later”” each day during a trial period, is often used.

Once the desired time schedule has been achieved, it is fundamental that the patient strictly comply with this sleep/wake schedule. Avoiding bright lights in the afternoon hours can also help. Additionally, a dawn-simulator lighting system can help advance or delay the start/end of the patient´s circadian rhythm.

Patients affected by FASPS / FDSPS have to accept the fact that they have a permanent disability and that their quality of life can only be improved by treatment.


  • PER2
  • CSNK1D