Sleep and the Autonomic Nervous System in Long COVID and ME/CFS: Why Rest Often Doesn't Come

Many people living with Long COVID or ME/CFS describe the same paradox: they sleep for what seems like enough hours, yet wake up exhausted. Researchers call this non-restorative sleep, and it is considered a core feature of both conditions. How long someone sleeps appears to matter less than how that sleep is structured and how the autonomic nervous system behaves during it.

The autonomic nervous system unconsciously regulates heart rate, blood pressure, breathing, digestion, and body temperature. In Long COVID, ME/CFS, and postural orthostatic tachycardia syndrome (POTS), studies repeatedly point to autonomic dysregulation — an imbalance between the activating (sympathetic) and calming (parasympathetic) branches of this system. A 2025 study published in PLOS ONE describes a shared autonomic profile across Long COVID and ME/CFS, marked by elevated baseline sympathetic activity — in other words, a nervous system that struggles to "power down" even at rest. Yet that powering down is exactly what deep, restorative sleep requires.

What actually happens overnight

Sleep studies in ME/CFS and Long COVID show recurring patterns: more frequent brief arousals, an altered ratio of deep to light sleep, and so-called alpha-delta sleep, in which wake-like brainwave activity intrudes into deep sleep stages. The brain is thus partly caught between wakefulness and sleep — the body rests without fully recovering. Observations also point to disrupted circadian rhythms: a review published in eClinicalMedicine describes evidence in post-infectious fatigue conditions, including Long COVID, of a disturbed internal clock that can affect sleep timing, hormone release, and available energy throughout the day.

In POTS, another mechanism adds to the picture: lying down shifts more blood toward the lower body, which can contribute to fluctuating heart rate and a sense of restlessness or palpitations when falling asleep or waking during the night. The patient organization Dysautonomia International notes that sleep problems are very common in dysautonomia and closely tied to autonomic regulation itself, not only to external disturbances.

Sleep-supporting habits that may help

The UK's NICE guideline (NG206) and the US CDC outline similar core principles for approaching sleep difficulties in ME/CFS. These principles can also apply to Long COVID and POTS when adapted to individual capacity:

• Consistent sleep and wake times, as capacity allows — including weekends — to help stabilize the internal clock.
• Morning light exposure, and brief time outdoors when possible, to support circadian rhythm.
• Reduced screen and light exposure in the evening, especially during the last hour before bed.
• A cool, dark, quiet bedroom reserved for sleep alone, where practical.
• Avoiding caffeine and heavy meals in the late afternoon and evening.
• A calm wind-down period before bed rather than strenuous activity right beforehand, to avoid sympathetic overactivation.
• Deliberate pacing during the day: overexertion and subsequent crashes can further disrupt nighttime restlessness and sleep quality.
• For lying-down heart rate restlessness linked to POTS, some people report relief from slightly elevating the head of the bed — this should be considered individually and discussed with a treating clinician.

Recognizing the limits of self-help

Sleep hygiene can support wellbeing, but it does not resolve the underlying autonomic dysregulation. NICE explicitly notes that no single approach can be considered universally effective for everyone with ME/CFS, and individual differences in capacity must be respected. Anyone noticing persistently severe sleep disruption, nighttime racing heart episodes, or breathing pauses should have this evaluated by a clinician, since other causes such as sleep apnea can also play a role.

Conclusion

Non-restorative sleep in Long COVID, ME/CFS, and POTS is not a sign of poor discipline — current research suggests it reflects a genuine autonomic and sleep-architecture difference. Consistent routines, a low-stimulation sleep environment, and mindful energy management throughout the day can improve the conditions for recovery, even though they do not resolve the underlying regulatory disturbance. Tracking one's own patterns of activity, exhaustion, and sleep quality over time can make it easier to see which habits genuinely make a difference in daily life.

This article is for general information only and does not replace individual medical advice.