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Young adult male students participated in a naturalistic, group-design experiment to ascertain the effects of one night's total sleep deprivation (TSD) on performance of diverse executive function tasks presented as an extended, multitask battery. On the majority of component tasks in this battery, performance has been reported to be impaired following one night's TSD when tasks are administered in isolation. However, participants sleep deprived 35 to 39 hr showed few performance deficits among tests in this battery when compared with non-sleep-deprived controls. Sleep-deprived participants showed only poorer recognition memory and overconfidence in incorrect temporal judgments. Behavioral and physiological adaptation to chronically sleep-restricting lifestyles may confer resistance to the cognitive effects of sleep deprivation in high-functioning young adults.

Thinking is known to be state dependent but a systematic study of how thinking in dreams differs from thinking while awake has not been done. The study consisted of analyzing the dream reports of 26 subjects who, in addition to providing dream reports also provided answers to questions about their thinking within the dream. Our hypothesis was that thinking in dreams is not monolithic but has two distinct components, one that is similar to wake-state cognition, and another that is fundamentally different. We found that cognition within a dream scenario was similar to that of wake-state cognition, but that thinking about the scenario itself was deficient and very different than wake-state thinking.

Flexible or 'fluid' cognitive processes are regarded as fundamental to problem solving and creative ability, requiring a specific neurophysiological milieu. REM-sleep dreaming is associated with creative processes and abstract reasoning with increased strength of weak associations in cognitive networks. REM sleep is also mediated by a distinctive neurophysiological profile, different to that of wake and NREM sleep. This study compared the performance of 16 subjects on a test of cognitive flexibility using anagram word puzzles following REM and NREM awakenings across the night, and waking performances during the day. REM awakenings provided a significant 32% advantage in the number of anagrams solved compared with NREM awakenings and was equal to that of wake time trials. Correlations of individual performance profiles suggest that REM sleep may offer a different mode of problem solving compared with wake and NREM. When early and late REM and NREM awakening data were separated, a dissociation was evident, with NREM task performance becoming more REM-like later in the night, while REM performance remained constant. These data suggest that the neurophysiology of REM sleep represents a brain state more amenable to flexible cognitive processing than NREM and different from that in wake, and may offer insights into the neurocognitive properties of REM-sleep dreaming.

Sleep can be addressed across the entire hierarchy of biological organization. We discuss neuronal-network and regional forebrain activity during sleep, and its consequences for consciousness and cognition. Complex interactions in thalamocortical circuits maintain the electroencephalographic oscillations of non-rapid eye movement (NREM) sleep. Functional neuroimaging affords views of the human brain in both NREM and REM sleep, and has informed new concepts of the neural basis of dreaming during REM sleep -- a state that is characterized by illogic, hallucinosis and emotionality compared with waking. Replay of waking neuronal activity during sleep in the rodent hippocampus and in functional images of human brains indicates possible roles for sleep in neuroplasticity. Different forms and stages of learning and memory might benefit from different stages of sleep and be subserved by different forebrain regions.

This study investigated the relationship between dream emotion and dream character identification. Thirty-five subjects provided 320 dream reports and answers to questions on characters that appeared in their dreams. We found that emotions are almost always evoked by our dream characters and that they are often used as a basis for identifying them. We found that affection and joy were commonly associated with known characters and were used to identify them even when these emotional attributes were inconsistent with those of the waking state. These findings are consistent with the finding that the dorsolateral prefrontal cortex, associated with short-term memory, is less active in the dreaming compared to the wake brain, while the paleocortical and subcortical limbic areas are more active. The findings are also consistent with the suggestion that these limbic areas have minimal input from the dorsolateral prefrontal cortex in the dreaming brain., (Copyright 2002 Elsevier Science (USA).)

Bill Domhoff (2005) has challenged the activation synthesis model of dreaming on the basis of a misreading of the neurobiological literature and an individualistic view of dream psychology. The author begins his reply by clarifying and emphasizing the formal approach to dream cognitions. Instead of focusing on the individual aspects of dreaming that interest Domhoff activation synthesis strives to identify and measure the generic differences that characterize all dreams and that are likely to correlate with the neurobiological findings. He then goes on to point out that such formal features as the visuomotor imagery, the emotional intensification, and the defective cognition of dreams do correlate with the cellular and molecular neurobiological data from animal studies and with the brain imaging and lesion data from human studies. individual differences may also exist but these are not relevant to the main task of sleep psychophysiology. [ABSTRACT FROM AUTHOR]