Research
Hormonal
REM sleep is characterized by sympathetic predominance and vagal withdrawal, leading to reduced cardiovascular complexity and increased stress vulnerability, particularly in aging populations.
Understand that REM sleep is not a passive rest period but a state of high autonomic activity. This is normal, but it means your cardiovascular system is under more stress during this phase, especially as you age. Prioritizing sleep quality and managing stress during the day may help mitigate the sympathetic load during REM.
GoodSupportsHIGH confidence
the rapid eye movement (REM) stage is characterized by a likely sympathetic predominance associated with a vagal withdrawal... supporting the hypothesis of a reduced capability of the cardiovascular system to deal with stress challenges.
Why this rating
Based on a comprehensive review of multiple studies (linear and non-linear HRV analyses) across different populations.
Source
Heart rate variability in normal and pathological sleep
Eleonora Tobaldini et al. · Frontiers in Physiology · 2013
DOI 10.3389/fphys.2013.00294
narrative_reviewCited 371×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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- Obstructive Sleep Apnea (OSA) causes chronic sympathetic hyperactivation and reduced cardiovascular complexity, which is partially reversible with Continuous Positive Airway Pressure (CPAP) therapy.Good
- Non-REM (NREM) sleep is characterized by increased parasympathetic modulation and higher cardiovascular complexity compared to REM sleep, serving as a restorative phase.Good
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