Nearly 200 studies have examined the impact that either acute or long-term exercise has upon cognition. Subsets of these studies have been reviewed using the traditional narrative method, and the common conclusion has been that the results are mixed. Therefore, a more comprehensive review is needed that includes all available studies and that provides a more objective and reproducible review process. Thus, a meta-analytic review was conducted that included all relevant studies with sufficient information for the calculation of effect size (N = 134). The overall effect size was 0.25, suggesting that exercise has a small positive effect on cognition. Examination of the moderator variables indicated that characteristics related to the exercise paradigm, the participants, the cognitive tests, and the quality of the study influence effect size. However, the most important finding was that as experimental rigor decreased, effect size increased. Therefore, more studies need to be conducted that emphasize experimental rigor.

/pdf/the-influence-of-physical-fitness-and-exercise-upon-11zj3fe3mn.pdf

The Influence of Physical Fitness and Exercise upon Cognitive Functioning: A Meta-Analysis

Converging evidence and new research methodologies from across the neurosciences permit the neuroscientific study of the role of sleep in off-line memory reprocessing, as well as the nature and function of dreaming. Evidence supports a role for sleep in the consolidation of an array of learning and memory tasks. In addition, new methodologies allow the experimental manipulation of dream content at sleep onset, permitting an objective and scientific study of this dream formation and a renewed search for the possible functions of dreaming and the biological processes subserving it.

https://www.cogsci.ucsd.edu/~pineda/COGS175/readings/Stickgold.pdf

Sleep, learning, and dreams: off-line memory reprocessing

The effects of sleep deprivation on the neural substrates of cognition are poorly understood. Here we used functional magnetic resonance imaging to measure the effects of 35 hours of sleep deprivation on cerebral activation during verbal learning in normal young volunteers. On the basis of a previous hypothesis1, we predicted that the prefrontal cortex (PFC) would be less responsive to cognitive demands following sleep deprivation. Contrary to our expectations, however, the PFC was more responsive after one night of sleep deprivation than after normal sleep. Increased subjective sleepiness in sleep-deprived subjects correlated significantly with activation of the PFC. The temporal lobe was activated after normal sleep but not after sleep deprivation; in contrast, the parietal lobes were not activated after normal sleep but were activated after sleep deprivation. Although sleep deprivation significantly impaired free recall compared with the rested state, better free recall in sleep-deprived subjects was associated with greater parietal lobe activation. These findings show that there are dynamic, compensatory changes in cerebral activation during verbal learning after sleep deprivation and implicate the PFC and parietal lobes in this compensation.

Altered brain response to verbal learning following sleep deprivation

Maintenance of wakefulness test: A polysomnographic technique for evaluating treatment efficacy in patients with excessive somnolence ☆

Ten male subjects were studied for a total of 306 days on self-selected schedules Four of them developed bedrest-activity cycle period lengths very different from 24 hr (mean = 368 hr) despite the persistence of near-24-hr oscillations in other physiologic functions, including that of body temperature (mean = 246 hr) The percentage of sleep time spent in REM sleep varied significantly with the phase of that near-24-hr body temperature cycle The peak in REM sleep propensity (RSP) occurred on the rising slope of the average body temperature curve, coincident with the phase of peak sleep tendency This was associated with a significantly increased REM episode duration and shortened REM latency (including sleep-onset REM episodes), but without a significant change in the REM-NREM cycle length We conclude that there is an endogenous circadian rhythm of REM sleep propensity which is closely coupled to the body temperature rhythm and is capable of free-running with a period different from both 24 hr and the average period of the sleep-wake cycle

Timing of REM sleep is coupled to the circadian rhythm of body temperature in man.

: Young male Naval volunteers were denied normal nocturnal sleep and maintained on a 60-min treatment-160-min testing schedule for 40 consecutive hours Ten subjects bicycled, 20 subjects controlled EEG activity during bedrest, and 10 subjects napped Eight measures of addition, auditory vigilance, mood, and oral temperature were obtained The Bedrest group showed significant impairment on all eight measures, and thus, gave no support to the forced rest theory of sleep function The exercise group was worse than the Nap and Bedrest groups for all measures In spite of fragmented, reduced sleep (about 37 hours per 24 hours), the Nap group had no impairment on six of the measures The results suggest that exercise increases the impairment due to sleep loss, and naps reduce or remove this impairment

Effects of Exercise, Bedrest and Napping on Performance Decrement During 40 Hours

Dynamics of nap sleep during a 40 hour period

Resolution and stability in the autospectra of EEG

Intra-hemispheric phase relationships during self-regulated alpha activity

: Changes in heart rate, respiratory rate, finger temperature and skin resistance to six stimuli on two occasions were examined in 30 young adult males The goals were to determine the degree of individual and stimulus response specificity and response stereotypy when difference scores and when autonomic lability scores (ALS) were used Results indicated ALS scores gave more significant results Individual response specificity was found in two thirds of our Ss but stimulus response specificity was not marked Response stereotypy, while present in many subjects, was very unstable from day to day Further data on the differential effect of law of initial values are presented which demonstrate the importance of a variable by variable approach when adjusting for prestimulus values (Author)

David J. Hord

Papers

Effects of Exercise, Bedrest and Napping on Performance Decrement During 40 Hours

Dynamics of nap sleep during a 40 hour period

Resolution and stability in the autospectra of EEG

Intra-hemispheric phase relationships during self-regulated alpha activity

Response specificity for difference scores and autonomic lability scores