REM sleep vs exploratory wakefulness: Alternatives within adult 'sleep debt'?

Area of Science:

• Neuroscience
• Sleep Science
• Developmental Biology

Background:

• Infant sleep duration decreases with development, primarily due to REM sleep loss.
• This decline correlates with increased infant locomotion and multisensory input, termed 'exploratory wakefulness' (EW).
• EW is crucial for neural restructuring and behavioral adaptations (neuroplasticity).

Purpose of the Study:

• To propose that REM sleep acts as a proxy for EW in promoting neuroplasticity.
• To investigate the necessity of REM sleep's inhibited locomotor output (atonia).
• To explore the role of EW in replacing some adult REM sleep and its implications for sleep duration and circadian rhythms.

Main Methods:

• Comparative analysis of infant and adult sleep patterns.
• Review of neurobiological evidence linking REM sleep, EW, and neuroplasticity.
• Examination of data on sleep duration in different populations (e.g., hunter-gatherers).

Main Results:

• REM sleep may serve as a functional equivalent to EW in driving neuroplasticity.
• Adults retain neotenous infant characteristics, including significant REM sleep.
• A portion of adult REM sleep, particularly in the final sleep episode, can be substituted by EW without REM rebound.
• This substitution may explain seasonally shorter sleep durations and challenges the notion of widespread 'chronic sleep debt'.

Conclusions:

• Exploratory wakefulness (EW) plays a significant role in neuroplasticity, potentially substituting for REM sleep.
• Adult sleep duration is more adaptable than commonly believed, influenced by EW and circadian factors.
• The study questions the severity of chronic sleep debt in Western societies and refutes claims linking REM sleep absence to obesity.