THC Before Bed Disrupts Sleep Stages and Reduces Heart Rate Variability | Research

The takeaway

Acute THC administration before sleep increased sleep latency and slow-wave sleep but markedly reduced cardiac parasympathetic activity, suggesting potential cardiovascular risks from bedtime cannabis use.

People using cannabis as a sleep aid, sleep medicine professionals, cardiologists, and cannabis researchers studying physiological effects.

What the researchers found

Acute THC before bedtime increased sleep latency and slow-wave sleep while markedly reducing heart rate variability across time- and frequency-domain measures during sleep, indicating reduced cardiac parasympathetic activity — and regular cannabis users showed shorter total sleep time and greater disruption at home.

Why it matters

Many people use cannabis specifically to sleep better, but this study reveals that THC may actually increase cortical activation and reduce heart-protective parasympathetic tone during sleep.

The numbers in context

n=18 (9 regular users, 9 minimal exposure); regular users had shorter total sleep time at home (p significant); acute THC increased sleep latency and slow-wave sleep (p significant); HRV reduced across time- and frequency-domain (p significant)

How the study worked

Feasibility and mechanistic pilot study comparing 9 regular cannabis users (>3x/week) and 9 minimal-exposure adults, with controlled in-lab THC dosing and at-home monitoring using polysomnography and cardiac autonomic measures.

What this study cannot tell us

Very small sample (n=18); pilot/feasibility study not powered for definitive conclusions; ad libitum home cannabis use in regular user group; single acute dose may not reflect chronic use patterns; no long-term follow-up.

How to read the evidence

Small pilot study with objective physiological measurements (PSG, HRV) providing mechanistic insights, but very limited sample size prevents clinical conclusions.

When this study was published

Published 2026; represents current understanding of acute THC-sleep physiology.

The bigger picture

As millions use cannabis as a sleep aid, evidence that THC disrupts autonomic regulation during sleep raises important cardiovascular safety questions that warrant larger-scale investigation.

Questions still open

Does chronic THC use lead to sustained HRV reduction during sleep? Is CBD without THC safer for sleep? Do these cardiovascular effects increase long-term cardiac risk?

Common questions

Does THC help or hurt sleep?

This pilot study found mixed effects — THC increased slow-wave (deep) sleep but also increased the time to fall asleep and significantly reduced heart rate variability, a marker of cardiovascular health during sleep.

Is using cannabis before bed safe for your heart?

This small study found that THC markedly reduced cardiac parasympathetic activity during sleep, which could signal cardiovascular risk — but larger studies are needed to confirm this and assess long-term implications.

Read the original research

Delta-9-Tetrahydrocannabinol (THC) Before Bedtime: Feasibility and Mechanistic Pilot Study on Sleep and Cardiac Autonomic Activity.

Journal of sleep research, e70298

View on PubMed ↗Publisher’s paper ↗

Citation

Gonzalez, Joshua E; Stewart, Alicia V; Ellison, Jacquelin L; Ordaz, Omar H; Robinson, LaTroy D; Clemons, Noal A; Emens, Jonathan S; Rice, Sean P M; Shea, Steven A; Bowles, Nicole P. (2026). Delta-9-Tetrahydrocannabinol (THC) Before Bedtime: Feasibility and Mechanistic Pilot Study on Sleep and Cardiac Autonomic Activity.. Journal of sleep research, e70298. https://doi.org/10.1111/jsr.70298