Definition
Sleep and vigilance evolved as an intricate compromise — the brain must rest and consolidate while remaining monitorable for danger. Traces of that ancestral bargain still shape sleep architecture and disturbances today.
Why it matters
Understanding sleep as an ancestral vigilance compromise clarifies why some sleep problems appear only under threat, and why safety changes sleep.
The Science
Group sleeping likely shaped human sleep patterns, and individual variation in "sentinel" behavior has been proposed as adaptive. Sleep in humans is highly context-sensitive to perceived safety.
The NSI Perspective
NSI treats context-sensitive sleep as intelligent nervous-system function, not defect.
Clinical Implications
Building perceived safety (physical, social, emotional) is legitimate sleep intervention.
Practical Application
If you sleep poorly when unsafe or alone, that is not fragility. That is ancient design.
References
- 1.Samson DR, Crittenden AN, Mabulla IA, Mabulla AZP, Nunn CL. Chronotype variation drives night-time sentinel-like behaviour in hunter-gatherers. Proc Biol Sci. 2017;284(1858):20170967.