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Dynastic cycle (traditional Chinese: 朝代循環; simplified Chinese: 朝代循环; pinyin: Cháodài Xúnhuán) is an important political theory in Chinese history. According to this theory, each dynasty of China rises to a political, cultural, and economic peak and then, because of moral corruption, declines, loses the Mandate of Heaven ...
The basic rest–activity cycle (BRAC) is a physiological arousal mechanism in humans proposed by Nathaniel Kleitman, [1] hypothesized to occur during both sleep and wakefulness. Empirically, it is an ultradian rhythm of approximately 90 minutes (80–120 minutes [ 2 ] ) characterized by different levels of excitement and rest.
The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). [1]
The traditional lens for viewing Chinese history is the dynastic cycle: imperial dynasties rise and fall, and are ascribed certain achievements. Throughout pervades the narrative that Chinese civilization can be traced as an unbroken thread many thousands of years into the past , making it one of the cradles of civilization .
The state of grogginess, impaired cognition and disorientation experienced when awakening from sleep is known as sleep inertia. [16] This state reduces the speed of cognitive tasks but has no effects on the accuracy of task performance. [4] The effects of sleep inertia rarely last longer than 30 minutes in the absence of prior sleep deprivation ...
For most of its history, China was organized into various dynastic states under the rule of hereditary monarchs.Beginning with the establishment of dynastic rule by Yu the Great c. 2070 BC, [1] and ending with the abdication of the Xuantong Emperor in AD 1912, Chinese historiography came to organize itself around the succession of monarchical dynasties.
One of the important questions in sleep research is clearly defining the sleep state. This problem arises because sleep was traditionally defined as a state of consciousness and not as a physiological state, [14] [15] thus there was no clear definition of what minimum set of events constitute sleep and distinguish it from other states of partial or no consciousness.
REM sleep typically occupies 20–25% of total sleep in adult humans: about 90–120 minutes of a night's sleep. The first REM episode occurs about 70 minutes after falling asleep. Cycles of about 90 minutes each follow, with each cycle including a larger proportion of REM sleep. [27]