Final answer:
The concept you're asking about aligns with the Adaptive theory of sleep, which suggests that the duration and timing of sleep are evolutionary adaptations to maximize survival, rather than merely to restore energy. This theory is contrasted with the restorative theory, which ties sleep length to energy recovery, and research data does not consistently support this idea.
Step-by-step explanation:
The hypothesis that each species has evolved a specific time-window for sleeping, and the length of this window varies across species, directly relates to the Adaptive theory of sleep. Sleep patterns are thought to have evolved as an adaptive response to multiple factors, including predation and energy conservation. The restorative theory, by contrast, focuses on sleep needing to restore resources expended during the day, and the information processing theory emphasizes the role of sleep in memory consolidation and learning. The activation-synthesis model is specific to dreaming and posits that dreams result from the brain's attempt to make sense of neural activity during REM sleep, rather than an evolutionary adaptation of sleep itself.
Regarding your question about species and window of sleep duration, if the restorative theory is correct, you would expect species with higher levels of energy expenditure to sleep longer, as they need more time to recover. However, this is not consistently supported by empirical data. Alternatively, the adaptive theory would suggest that sleeping patterns, including the duration and timing, have evolved to maximize survival chances, not just to restore energy, and may not directly correlate with daily energetic demands.