Sleep promotes offline enhancement of an explicitly learned discrete but not an explicitly learned continuous task

Catherine F Siengsukon, Alham Al-SharmanDepartment of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, USABackground: Healthy young individuals benefit from sleep to promote offline enhancement of a variety of explicitly learned discrete motor tasks. It remains unknown if sleep will promote learning of other types of explicit tasks. The purpose of this study is to verify the role of sleep in learning an explicitly instructed discrete motor task and to determine if participants who practice an explicitly instructed continuous tracking task demonstrate sleep-dependent offline learning of this task.Methods: In experiment 1, 28 healthy young adults (mean age 25.6 ± 3.8 years) practiced a serial reaction time (SRT) task at either 8 am (SRT no-sleep group) or 8 pm (SRT sleep group) and underwent retention testing 12 ± 1 hours later. In experiment 2, 20 healthy young individuals (mean age 25.6 ± 3.3 years) practiced a continuous tracking task and were similarly divided into a no-sleep (continuous tracking no-sleep group) or sleep group (continuous tracking sleep group). Individuals in both experiments were provided with explicit instruction on the presence of a sequence in their respective task prior to practice.Results: Individuals in the SRT sleep group demonstrated a significant offline reduction in reaction time whereas the SRT no-sleep group did not. Results for experiment 1 provide concurrent evidence that explicitly learned discrete tasks undergo sleep-dependent offline enhancement. Individuals in the continuous tracking sleep group failed to demonstrate a significant offline reduction in tracking error. However, the continuous tracking no-sleep group did demonstrate a significant offline improvement in performance. Results for experiment 2 indicate that sleep is not critical for offline enhancement of an explicit learned continuous task.Conclusion: The findings that individuals who practiced an explicitly instructed discrete task experienced sleep-dependent offline learning while those individuals who practiced an explicitly instructed continuous task did not may be due to the difference in motor control or level of complexity between discrete and continuous tasks.Keywords: sleep, motor learning, discrete task, continuous tas

Sleep during low-frequency repetitive transcranial magnetic stimulation is associated with functional improvement in upper limb hemiparesis after stroke.

Many studies have reported that repetitive transcranial magnetic stimulation (rTMS) is beneficial for post-stroke patients with upper limb hemiparesis. It was reported that application of rTMS during sleep could possibly strengthen neural plasticity. The purpose of this study was to investigate the relationship between sleep during low-frequency rTMS session and improvement of motor function in affected upper limb in post-stroke patients after inpatient rehabilitation combined with rTMS using the bispectral index (BIS) monitor. During 15-day hospitalization, each patient received rTMS and intensive occupational therapy. Low-frequency rTMS with 1 Hz was applied over the contralesional motor cortex. During rTMS session, adhesive sensor was put on each patient's forehead and connected to the BIS monitor. The mean score for the maximum change of BIS values during each rTMS session (DeltaBIS) was calculated. We regarded the patients with and over 10 of mean DeltaBIS as Asleep group and under 10 as Awake group. Fugl-Meyer assessment (FMA) and Action Research Arm Test (ARAT) were evaluated on admission and discharge. Awake group included six patients and Asleep group included seven patients. There was no significant difference in clinical characteristics and in increase of FMA between two groups. Asleep group was significantly superior to Awake group in the increase of ARAT (p < 0.05). There was a significant correlation between the mean of DeltaBIS and increase of ARAT (rho = 0.78, p = 0.002). Sleep during low-frequency rTMS may contribute to improvement of motor function in the affected upper limb

Time to wake up: sleep problems and daytime sleepiness in long-term stroke survivors

Background and purpose: In work with chronic stroke patients the authors observed that patients frequently appear sleepy and often comment on their poor sleep. Sleep difficulties are frequently reported and indeed clinically recognized in the acute phase post-stroke, but little is known about the sleep and daytime sleepiness of chronic stroke patients with sustained disabilities. The latter, however, deserves clarification because sleep is a critical modulator of health, daytime performance and wellbeing. The present study therefore explored the sleep and sleepiness in a chronic stroke population with sustained physical deficits. Methods: An opportunity sample of 20 patients with chronic low-functioning hemiplegia (>12 months) completed the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Medical Outcome Study Short Form 36 and Hospital Anxiety and Depression Scale. Results: Compared to a normative healthy population, long-term stroke survivors reported poorer sleep and greater daytime sleepiness. Increased levels of sleepiness were associated with longer chronicity, whereas nocturnal sleep parameters were not. Conclusions: In line with clinical observations, stroke survivors with sustained physical disabilities report poorer sleep and experience greater levels of sleepiness. Further research in a larger cohort and including objective sleep measures is necessary to investigate the nature and scale of sleep difficulties and daytime sleepiness in more detail so that care and treatment strategies can be developed in due course