Biomedical subjects

Alexandra Morgan

Publications and source records attributed to Alexandra Morgan.

3 recordsLinked to original sources

PubMed2005

Sleep quality deteriorates over a binge--abstinence cycle in chronic smoked cocaine users.

RATIONALE: In cocaine dependent individuals, changes in subjective and objective sleep quality accompany their characteristic binge-abstinence cycle. Preliminary studies suggest that sleep quality may decline with prolonged abstinence. Reported here are results of the most extensive study to date on sleep abnormalities during cocaine binge and confirmed abstinence under controlled conditions. OBJECTIVES: The purpose of the current study was to use an experimental, inpatient model of the cocaine binge and abstinence cycle to examine the course and magnitude of sleep disturbances during cocaine use and abstinence. METHODS: Five inpatient non-treatment seeking cocaine users completed 3 baseline days of drug abstinence followed by 3 days of medically monitored "binge" cocaine use, and then 15 days of drug abstinence. Physiological sleep was recorded with polysomnography and the Nightcap ambulatory monitor, while subjective sleep was assessed by questionnaire. RESULTS: Across 3 days of binge cocaine use and 15 subsequent days of confirmed drug abstinence, mean sleep duration, efficiency and latency changed in the direction of poorer sleep quality. In contrast, subjective reports of sleep quality remained unchanged across the same period. CONCLUSIONS: Physiological sleep quality deteriorated from days when cocaine was used across the first 2 weeks of confirmed drug abstinence. In contrast, subjective reports of sleep quality remained unchanged across the same period. We postulate that this dissociation between objective and subjective sleep quality results from a cocaine-use related disruption of the sleep homeostat. Worsening sleep quality during cocaine abstinence may contribute to the risk of relapse and its treatment may offer novel therapeutic strategies for cocaine dependence.

Adult↗

PubMed2002

Practice with sleep makes perfect: sleep-dependent motor skill learning.

Improvement in motor skill performance is known to continue for at least 24 hr following training, yet the relative contributions of time spent awake and asleep are unknown. Here we provide evidence that a night of sleep results in a 20% increase in motor speed without loss of accuracy, while an equivalent period of time during wake provides no significant benefit. Furthermore, a significant correlation exists between the improved performance overnight and the amount of stage 2 NREM sleep, particularly late in the night. This finding of sleep-dependent motor skill improvement may have important implications for the efficient learning of all skilled actions in humans.

Adolescent↗

PubMedDate not supplied

Sleep and the time course of motor skill learning.

Growing evidence suggests that sleep plays an important role in the process of procedural learning. Most recently, sleep has been implicated in the continued development of motor-skill learning following initial acquisition. However, the temporal evolution of motor learning before and after sleep, the effects of different training regimens, and the long-term development of motor learning across multiple nights of sleep remain unknown. Here, we report data for subjects trained and retested on a sequential finger-tapping task across multiple days. The findings demonstrate firstly that following initial training, small practice-dependent improvements are possible before, but not following the large practice-independent gains that develop across a night of sleep. Secondly, doubling the quantity of initial training does not alter the amount of subsequent sleep-dependent learning that develops overnight. Thirdly, the amount of sleep-dependent learning does not correlate with the amount of practice-dependent learning achieved during training, suggesting the existence of two discrete motor-learning processes. Finally, whereas the majority of sleep-dependent motor-skill learning develops during the first night of sleep following training, additional nights of sleep still offer continued improvements.

Adult↗