Investigating the Impact of Sleep Deprivation on Autonomic Nervous System Regulation and Cardiovascular Responsiveness in Young Adults

Project Abstract

Sleep deprivation is a pervasive lifestyle factor with potential to disrupt autonomic nervous system (ANS) regulation and cardiovascular responsiveness in young adults, a demographic increasingly exposed to irregular sleep schedules and shift work. This study investigates the acute and subacute effects of partial and total sleep deprivation on autonomic balance, baroreflex sensitivity, heart rate variability (HRV), and cardiovascular reactivity to stressors. A mixed-methods design was employed, combining quantitative physiological measurements with qualitative self-reports to capture both objective autonomic changes and subjective sleep-related symptoms. A sample of 120 healthy university students aged 18–30 was recruited and randomized into three groups control (normal sleep), partial sleep deprivation (restricted to 4 hours/night for three consecutive nights), and total sleep deprivation (24 hours awake). Baseline assessments included HRV in time and frequency domains, resting blood pressure, pulse wave velocity, and circulating catecholamines as indices of sympathetic activity. Follow-up measurements were obtained after the deprivation protocol and again after a recovery period of 48 hours with normal sleep. Stress reactivity was evaluated using a standardized mental arithmetic task and a cold pressor test, with concurrent monitoring of HRV, heart rate, BP, and perceived stress. The study also examined circadian influences by scheduling sessions at consistent times and controlling for caffeine intake, physical activity, and hydration. Data analysis employed mixed-model repeated measures to assess within-subject changes across conditions and between-group differences, with adjustments for age, sex, BMI, and baseline fitness. Primary outcomes focused on HRV indices reflecting autonomic balance, including high-frequency power as a marker of parasympathetic activity and low-frequency to high-frequency (LF/HF) ratio as an index of sympathovagal balance, alongside baroreflex sensitivity derived from spontaneous sequence analysis. Secondary outcomes encompassed resting and reactive blood pressure, arterial stiffness, and circulating catecholamines. The results indicated that partial sleep deprivation produced a significant reduction in HRV parasympathetic activity and a shift toward sympathetic dominance at rest, accompanied by modest elevations in systolic BP and reduced baroreflex sensitivity. Total sleep deprivation amplified these effects, with pronounced sympathetic activation, elevated heart rate, increased arterial stiffness, and impaired hemodynamic recovery after stress, compared to controls. Recovery sleep partially reinstated autonomic balance but residual autonomic dysregulation persisted at 48 hours in the total deprivation group. Qualitative findings revealed increased perceived fatigue, mood lability, and cognitive complaints correlating with objective autonomic disruption. Subgroup analyses suggested sex-specific differences, with women exhibiting more pronounced parasympathetic withdrawal under partial deprivation, while men demonstrated greater sympathetic surges under total deprivation. The study underscores the critical role of adequate sleep for maintaining autonomic stability and cardiovascular resilience in young adults, with implications for academic performance, accident risk, and long-term cardiovascular health. Limitations include reliance on laboratory-induced stressors and potential Hawthorne effects, suggesting avenues for future longitudinal field studies and exploration of moderating factors such as fitness level, chronotype, and genetic predispositions.

Project Overview

What This Project Is About

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This project looks at how skipping sleep affects the body’s automatic control systems and heart-related responses in healthy young adults. It studies how fatigue changes the balance between the sympathetic and parasympathetic branches of the autonomic nervous system and how these changes affect heart rate, blood pressure, and the body’s ability to respond to stress.

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The Problem It Addresses

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Many people, especially students and shift workers, don’t get enough sleep. This can disrupt automatic body regulation and potentially increase risk of cardiovascular issues. The study fills gaps in understanding how short-term sleep loss alters everyday bodily stress responses in young adults, a group at a critical life stage for long-term health.

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Objectives of the Project

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1. Describe baseline autonomic function and cardiovascular responses in well-rested young adults.
2. Assess changes in autonomic regulation after a controlled period of sleep deprivation.
3. Measure how these changes affect heart rate, blood pressure, and stress responses during mild challenges.
4. Evaluate the usefulness of simple noninvasive markers to detect sleep-loss–related autonomic changes.

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What You Will Do Step by Step

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1. Review literature on sleep, autonomic nervous system, and cardiovascular responses.
2. Recruit healthy young adult participants and screen for health criteria.
3. Record baseline cardiovascular and autonomic measures (e.g., heart rate variability, blood pressure).
4. Introduce a controlled sleep deprivation protocol and monitor responses.
5. Collect data during rest and light stress tasks to assess reactivity.
6. Analyze data for changes in autonomic balance and cardiovascular metrics.
7. Interpret findings and compare with existing evidence.
8. Prepare a concise report and presentation of methods and results.

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Expected Outcome

Anticipated findings include a measurable shift toward sympathetic dominance and altered heart rate and blood pressure responses after sleep loss. The project aims to identify practical, noninvasive indicators of sleep deprivation effects, contributing to guidelines for healthier sleep habits and risk awareness in young adults.