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Jan 07, 2010

Sleep contribution to motor memory consolidation: a motor imagery study

Sleep contribution to motor memory consolidation: a motor imagery study.

Sleep. 2009 Dec 1;32(12):1559-65

Authors: Debarnot U, Creveaux T, Collet C, Doyon J, Guillot A

STUDY OBJECTIVES: Sleep is known to enhance performance following physical practice (PP) of a new sequence of movements. Apart from a pilot study, it is still unknown whether a similar sleep-dependent consolidation effect can be observed following motor imagery (MI) and whether this mnemonic process is related to MI speed. DESIGN: Counterbalanced within-subject design. SETTING: The laboratory. PARTICIPANTS: Thirty-two participants. INTERVENTIONS: PP, real-time MI, fast MI, and NoSleep (control) groups. MEASUREMENTS AND RESULTS: Subjects practiced an explicitly known sequence of finger movements, and were assigned to PP, real-time MI, or fast MI, in which they intentionally imagined the sequence at a faster pace. A NoSleep group subjected to real-time MI, but without any intervening sleep, was also tested. Performance was evaluated before practice, as well as prior to, and after a night of sleep or a similar time interval during the daytime. Compared with the NoSleep group, the results revealed offline gains in performance after sleep in the PP, real-time MI, and fast MI groups. There was no correlation between a measure of underestimation of the time to imagine the motor sequence and the actual speed gains after sleep, neither between the ease/difficulty to form mental images and performance gains. CONCLUSIONS: These results provide evidence that sleep contributes to the consolidation of motor sequence learning acquired through MI and further suggests that offline delayed gains are not related to the MI content per se. They extend our previous findings and strongly confirm that performance enhancement following MI is sleep dependent.

Jul 01, 2009

Positive impact of cyclic meditation on subsequent sleep

Positive impact of cyclic meditation on subsequent sleep.

Med Sci Monit. 2009 Jul;15(7):CR375-381

Authors: Patra S, Telles S

Background: Cyclic meditation (CM) is a technique that combines yoga postures interspersed with supine rest. This combination is based on ancient texts and is considered easier for beginners to practice. Material/Methods: Whole-night polysomnographic measures and the self-rating of sleep were studied on the night following a day in which 30 male participants practiced CM twice (ca. 23 minutes each time). This was compared with another night when they had had two sessions of supine rest (SR) of equal duration on the preceding day. The sessions were one day apart and the order of the sessions was randomized. Recordings were from the F4, C4, and O2 electrode sites referenced to linked earlobes and bipolar electroculography and electromyography sites. Results: In the night following CM, the percentage of slow-wave sleep (SWS) was significantly higher than in the night following SR, whereas the percentage of rapid-eye-movement (REM) sleep and the number of awakenings per hour were less. Following CM the self-rating of sleep based on visual analog scales showed an increase in the feeling that the sleep was refreshing, an increase in feeling "good" in the morning, an overall increase in sleep duration, and decreases in the degree to which sleep was influenced by being in a laboratory as well as any associated discomfort. Conclusions: Practicing cyclic meditation twice a day appeared to improve the objective and subjective quality of sleep on the following night.