Evaluating daytime alertness in individuals with Restless Legs Syndrome (RLS) compared to sleep restricted controls.

BACKGROUND AND PURPOSE: Restless Legs Syndrome (RLS) is a common sensorimotor disorder often associated with significant chronic sleep loss. Previous studies looking at the effects of sleep loss on daytime function in RLS individuals, using subjective reporting techniques have yielded mixed results. In this study we used more objective measures of alertness and compared RLS subjects who are off treatments and chronically sleep restricted to chronic sleep-restricted controls. SUBJECTS AND METHODS: The final sample consisted of 20 RLS subjects (10 male and 10 female) and 13 sleep-restricted controls (seven male and six female). Thirteen controls underwent a 14-day chronic partial sleep-restriction protocol in order to closely match the degree of chronic sleep loss reportedly experienced by untreated RLS patients. On the final day of the protocol each subject performed a morning and evening Suggested Immobilization Test (SIT) which served as a modified Maintenance of Wakefulness Test (MWT). RLS and control groups were compared for differences in alertness as measured objectively by the sleep latency on the morning and evening SITs. RESULTS: The RLS subjects had a longer sleep latency on the morning and evening SIT than controls (t=3.80, p=0.001, U=31.0, p<0.001, respectively). Even after controlling for the potential arousal impact associated with increased leg activity, RLS individuals still demonstrated a higher degree of objective alertness (p=0.023, p=0.006, Fisher's exact test). CONCLUSIONS: RLS subjects, despite having, if anything, greater sleep loss, displayed greater sustained alertness than sleep-restricted controls. Thus, the heightened degree of alertness demonstrated by RLS patients may be in contrast to the perceived impairment in mood, vigor, and vigilance commonly reported in previous studies.

Sleep disturbance in heavy marijuana users.

STUDY OBJECTIVE: To determine if recently abstinent, heavy marijuana (MJ) users show differences in polysomnographic (PSG) measures compared with a drug-free control group. DESIGN: A group of carefully selected heavy MJ users were chosen for study inclusion and matched to a drug-free control group. Questionnaire data were collected prior to cessation of MJ use. PSG studies were conducted during 2 consecutive nights after discontinuation of MJ use in our core sleep laboratory. SETTING: Baltimore Maryland, General Clinical Research Center (GCRC) core sleep lab. PARTICIPANTS: 17 heavy MJ users discontinuing MJ use and 14 drug-free controls. Men and women were studied, 18 to 30 years. The MJ users reported no other drug use and alcohol use was negligible in both groups. Urine was positive for metabolites of cannabis only. MEASUREMENTS AND RESULTS: The MJ users showed differences in PSG measures (lower total sleep times, and less slow wave sleep than the control group) on both nights; they also showed worse sleep efficiency, longer sleep onset, and shorter REM latency than the control group on Night 2. More sleep continuity parameters were significantly worse for the MJ group than the control group on Night 2 versus Night 1, indicating that sleep in the MJ group was relatively worse on Night 2 compared to Night 1. The MJ group did not show improved sleep after an adaptation night as expected. Withdrawal symptoms, craving, and depression did not appear to influence these findings. CONCLUSIONS: During discontinuation of heavy MJ use, PSG measures of sleep disturbance were detected in MJ users compared with a drug-free control group. While this preliminary study cannot identify the extent to which these group differences were present before abstinence, poor sleep quality either prior to or after MJ discontinuation could result in treatment failure for MJ users. Further investigation is necessary to determine the association between the use and cessation of MJ and sleep disturbance.

A further evaluation of the cognitive deficits associated with restless legs syndrome (RLS).

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) is a common sensorimotor disorder that peaks in severity during the night and comes on with rest. As a result, this condition often results in significant chronic sleep loss, especially for those with severe disease. Chronic partial sleep restriction has been associated with conditions such as depression, anxiety, chronic pain, and decline in cognitive function. Furthermore, studies have found that RLS patients suffer from these conditions more than their unaffected peers. Thus, the morbidity rate associated with RLS has often been attributed to the chronic sleep loss that frequently accompanies this condition. However, no study has specifically compared RLS sufferers to otherwise normal sleep-restricted controls in order to assess disease morbidity independent of its sleep deprivation effects. In this study, we compared the cognitive function of RLS patients who were off treatment to sleep-restricted control subjects. SUBJECTS AND METHODS: A novel chronic partial sleep-restriction protocol that utilized a 14-day combined inpatient and outpatient design was implemented in order to test the differences in cognitive functioning between RLS patients and sleep-restricted controls. The brief cognitive battery included instruments assessing general intelligence and global executive function in order to control for baseline cognitive function between the groups, and then the effects of sleep loss were assessed using prefrontal lobe-specific tasks. The final sample consisted of 16 RLS (11 male and 5 female) and 13 sleep-restricted control subjects (7 male and 6 female). RESULTS: In order to examine the differences in cognitive functioning between sleep-restricted controls and RLS subjects, independent samples t-tests were conducted. RLS subjects performed significantly better on both the Letter Fluency (t=2.13, p<0.05) and Category Fluency (t=2.42, p<0.05) than sleep-restricted controls. CONCLUSIONS: RLS subjects performed better than the sleep-restricted controls on two tasks that are particularly sensitive to sleep loss. Although previous studies suggest that sleep deprivation may impact the cognitive function of those with RLS, our data suggests that RLS subjects may show a relative degree of sleep loss adaptation. Future investigations that more closely match the sleep loss pattern of RLS subjects to controls are warranted in order to explore these potential traits further.

Childhood and adult factors associated with restless legs syndrome (RLS) diagnosis.

BACKGROUND AND PURPOSE: RLS appears to be caused by a complex interaction of genetic and environmental factors. This study sought to identify some environmental risk factors significantly associated with the occurrence of RLS. PATIENTS AND METHODS: Three adult behaviors and 10 childhood factors potentially related to development of RLS were evaluated for significant association with the occurrence of RLS in a large case-controlled family history study. All available family members of the probands in this study were evaluated for RLS using a validated diagnostic telephone interview that included a background questionnaire covering factors potentially associated with the development of RLS. Where possible, the mothers of the subjects were also interviewed regarding developmental factors that might affect the child's health and perhaps occurrence of RLS. All family members with a definite diagnosis of RLS or Not-RLS were included in the study. Of a total of 973 participants, 262 (27%) had RLS and 711 did not. RESULTS: An odds ratio (OR) with 95% confidence limits (CI) was calculated for the relationship of each factor to RLS diagnosis. Restless sleep in childhood was associated with an increased risk of developing RLS later in life for both men (OR=2.64; 95% CI: 1.31-5.29) and women (OR=2.54; 95% CI: 1.41-4.59). Blood donation was also significantly associated with an increased risk of developing RLS among men only (OR=1.99; 95% CI: 1.10-3.58), which was more pronounced for those donating blood more than the median number of donations for this group of five (OR=2.3, 95% CI: 1.16-4.43). No other factor was significantly associated with the occurrence of RLS. CONCLUSIONS: This is the first case-controlled study that demonstrates a significant association between blood donation and the occurrence of RLS in males. The association was most significant for those men donating five or more times. Smoking and alcohol use were not related to the occurrence of RLS. Neither childhood growing pains nor attention-deficit hyperactivity disorder (ADHD) was related to RLS. The only consistent factor found related to prevalence of RLS for both men and women was the report of 'restless sleep' in childhood.