Narcolepsy and idiopathic hypersomnolence

Sleep, its regulation and possible mechanisms of sleep disturbances

The state of sleep consists of different phases that proceed in successive, tightly regulated order through the night forming a physiological program, which for each individual is different but stabile from one night to another. Failure to accomplish this program results in feeling of unrefreshing sleep and tiredness in the morning. The program core is constructed by genetic factors but regulated by circadian rhythm and duration and intensity of day time brain activity. Many environmental factors modulate sleep, including stress, health status and ingestion of vigilance-affecting nutrients or medicines (e.g. caffeine). Acute sleep loss results in compromised cognitive performance, memory deficits, depressive mood and involuntary sleep episodes during the day. Moreover, prolonged sleep curtailment has many adverse health effects, as evidenced by both epidemiological and experimental studies. These effects include increased risk for depression, type II diabetes, obesity and cardiovascular diseases. In addition to voluntary restriction of sleep, shift work, irregular working hours, jet lag and stress are important factors that induce curtailed or bad quality sleep and/or insomnia. This review covers the current theories on the function of normal sleep and describes current knowledge on the physiologic effects of sleep loss. It provides insights into the basic mechanisms of the regulation of wakefulness and sleep creating a theoretical background for understanding different disturbances of sleep.

Daytime sleepiness in elderly Parkinson's disease patients and treatment with the psychostimulant modafinil: A preliminary study

BACKGROUND

Patients with Parkinson's disease (PD) or Parkinsonian syndromes often report excessive daytime sleepiness (EDS). The aim of this study was to evaluate the effects of the psychostimulant modafinil on elderly, institutionalized, severely impaired PD patients with EDS.

METHOD

A three-week open study on ten institutionalized PD patients scoring >10 points on the Epworth Sleepiness Scale (ESS) with modafinil eventually on 100 mg twice a day. Patients were assessed at the start, week 1, and week 3 with ESS, Clinical Global Impression (CGI) scale severity of PD and appetite.

RESULTS

Reduction of ESS score and PD severity over time were found as well as a significant increase in appetite and reduction in CGI score.

CONCLUSION

Modafinil 100 mg twice a day was safe and modestly effective for the treatment of EDS in elderly, institutionalized PD patients. Sustaining wakefulness throughout all stages of PD is crucial for participating in life, maintaining social life, and improving quality of life.

From Club Drug to Orphan Drug: Sodium Oxybate (Xyrem) for the Treatment of Cataplexy

Narcolepsy, a rare disease with a prevalence of 0.05% in the general population, affects an estimated 140,000 patients in the United States. Patients have been able to lead fuller personal and professional lives since the Food and Drug Administration approved sodium oxybate (Xyrem) in 2002 for treatment of cataplexy in patients with narcolepsy. Previously, gamma-hydroxybutyrate (GHB), the active ingredient of sodium oxybate, had been a substance of abuse, most notoriously as a date-rape drug. Public Law 106-172, the date-rape prohibition act enacted in 2000, was modified to allow the drug to be legally administered for medical purposes. Because of the apprehension regarding the risk of possible drug diversion after the approval of sodium oxybate and concerns about safety, the Xyrem Risk Management Program was created. This program has been successful in satisfying the needs of patients and physicians while ensuring responsible distribution of the drug.

The role of prescribed napping in sleep medicine

Napping, when its timing and duration are designed properly, has the potential to improve our daily lives. Laboratory findings indicate that scheduled napping promotes waking function after normal sleep at night, and also counteracts decreased alertness and performance under conditions of sleep deprivation. Since these effects are evident even with naps shorter than 30 min, shiftwork problems may be alleviated by the short nap at the workplace. Multiple short naps are effective in managing excessive daytime sleepiness in narcoleptic patients under medication. The therapeutic usefulness of napping in other sleep disorders, however, remains to be established. Epidemiological studies suggest a decrease in the risk of cardiovascular and cognitive dysfunction by the practice of taking short naps several times a week. Sleep inertia occurs immediately after napping, but its severity can be minimized by avoiding long naps that may result in awakening from deep non-rapid eye movement sleep. Activities during the post-nap period should also be undertaken carefully. To allow the maximum advantage to be gained from napping, more efforts are needed to identify the strategies of napping that are compatible with individual cases including aging, work schedules, and sleep disorders, and to examine their efficacy in real-life settings.

DRB1*1502-DQB1*0601-DQA1*0103 and DRB1*04-DQB1*0302 in Jewish hypersomnolent patients

OBJECTIVES

Narcolepsy is a sleep disorder with a genetic association with the haplotype DRB1*1501, DQA1*0102, DQB1*0602. This haplotype has been described in different ethnic groups suffering from narcolepsy (Japanese, Caucasian, African Americans, Jews). In a recent study we have found the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in three patients with hypersomnolence. The similarity of this haplotype to the narcoleptic haplotype DRB1*1501, DQB1*0602 and DQA1*0102 has raised the question of whether this haplotype is a marker for sleepiness, or rather indicates a variant of non-cataplectic narcolepsy. This study was conducted to further investigate this question.

METHODS

HLA-DNA analysis was carried out in 20 healthy Jewish patients (age 23.9+/-6.3 years; 13 Ashkenazi, seven non-Ashkenazi) who had objective measures of hypersomnolence. All underwent whole-night polysomnography, multiple sleep latency test and tissue typing.

RESULTS

HLA-DNA analysis revealed HLA-DR2 in eight patients of whom five (25%) carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103 (vs. 1.4% in the Israeli population, P<0.0001). Six patients were diagnosed as non-cataplectic narcoleptics. Five of them carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103. Forty percent of the patients carried the haplotype DRB1*04, DQB1*0302, which was not statistically different from its prevalence in the healthy Israeli population (25%).

CONCLUSIONS

This is the first report describing the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in narcoleptic patients (non-cataplectic). This haplotype is close but different from the already known narcoleptic haplotype DRB1*1501, DQA1*0102, DQB1*0602. We assume that this haplotype represents a variant of non-cataplectic narcolepsy rather than association with hypersomnolence. However, in order to conclude whether this haplotype is a marker for the lack of cataplexy, or represents a variant of non-cataplectic narcolepsy, a larger group of patients should be investigated.