John Murphy, CEO, COVID-19 Long-haul Foundation
Abstract
Sleep disturbance has emerged as one of the most prevalent, persistent, and disabling manifestations of Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), commonly known as Long COVID. Although initially considered a secondary consequence of stress, hospitalization, or chronic illness, accumulating evidence suggests that sleep abnormalities may represent a core biological feature of Long COVID pathophysiology. Disturbances encompass insomnia, hypersomnia, circadian rhythm disorders, fragmented sleep architecture, sleep-disordered breathing, restless legs syndrome, parasomnias, and alterations in rapid eye movement (REM) and slow-wave sleep.
Recent investigations from the National Institutes of Health RECOVER Initiative have further suggested that preexisting sleep disorders may predispose individuals to Long COVID development through mechanisms involving glucocorticoid dysregulation, neuroimmune dysfunction, and impaired inflammatory resolution. Simultaneously, sleep disruption itself appears capable of amplifying many hallmark Long COVID symptoms including fatigue, cognitive dysfunction, autonomic instability, chronic pain, depression, anxiety, metabolic abnormalities, and impaired tissue repair.
The relationship between Long COVID and sleep is therefore bidirectional. SARS-CoV-2 infection disrupts sleep-regulating systems throughout the central nervous system, autonomic nervous system, endocrine networks, and immune pathways. Sleep disruption subsequently perpetuates inflammatory activation, mitochondrial dysfunction, and neurocognitive impairment, creating a self-sustaining pathophysiologic cycle.
This review examines current evidence regarding the epidemiology, physiology, pathology, diagnostic evaluation, therapeutic management, and long-term prognosis of sleep disorders associated with Long COVID. Particular emphasis is placed upon emerging mechanistic insights linking sleep biology to persistent viral injury, neuroinflammation, autonomic dysfunction, and impaired recovery.
Introduction
Since the emergence of SARS-CoV-2 in late 2019, attention has increasingly shifted from acute infection toward the prolonged multisystem syndrome known as Long COVID. Estimates suggest that between 10% and 30% of infected individuals experience persistent symptoms lasting months or years beyond the initial illness. Among these symptoms, sleep disturbances consistently rank among the most frequently reported.
Sleep complaints were observed during the earliest phases of the pandemic. Initially attributed to psychosocial stressors, quarantine conditions, and generalized anxiety, it became evident that many patients continued experiencing profound sleep abnormalities long after recovery from acute infection.
By 2024, multiple cohort studies demonstrated that sleep disorders were among the strongest predictors of reduced quality of life in Long COVID populations. Furthermore, disturbed sleep correlated strongly with fatigue severity, cognitive impairment, autonomic dysfunction, chronic pain, depression, and inability to return to work.
The significance of these observations extends beyond symptom management. Sleep represents a fundamental biologic process involved in immune regulation, metabolic homeostasis, neuroplasticity, tissue repair, glymphatic clearance, hormonal regulation, and memory consolidation. Consequently, persistent disruption may play a central role in sustaining Long COVID pathology.
Understanding this relationship requires examination of sleep not merely as a symptom but as a potentially critical mechanistic contributor to disease perpetuation.
Historical Perspective
Post-viral sleep disorders are not unique to COVID-19.
Sleep abnormalities have long been recognized following:
- Epstein-Barr virus infection
- Influenza
- Cytomegalovirus
- SARS-CoV-1
- Middle East Respiratory Syndrome (MERS)
- Human herpesvirus infections
Following the 1918 influenza pandemic, reports described prolonged fatigue, hypersomnolence, insomnia, and neuropsychiatric disturbances persisting months or years after infection.
Similarly, survivors of the 2003 SARS outbreak frequently reported chronic fatigue and disrupted sleep architecture years following recovery.
COVID-19 differs primarily in scale. Never before has a viral illness produced millions of survivors experiencing persistent sleep dysfunction simultaneously.
The pandemic therefore created an unprecedented natural experiment revealing the intricate relationships between infection, immunity, neurobiology, and sleep regulation.
Epidemiology
Incidence
Sleep disorders rank among the most common Long COVID manifestations.
Published studies generally report prevalence rates ranging from:
- 35% to 75% for insomnia symptoms
- 20% to 50% for excessive daytime sleepiness
- 15% to 40% for circadian rhythm disturbances
- 10% to 30% for sleep apnea exacerbation
- 5% to 15% for parasomnias and REM abnormalities
Meta-analyses suggest approximately 45% to 60% of Long COVID patients report clinically significant sleep disruption.
The variability reflects differences in:
- Diagnostic criteria
- Follow-up duration
- Population characteristics
- Vaccination status
- Severity of acute illness
Nevertheless, sleep disturbance consistently ranks among the top five reported Long COVID symptoms.
Demographic Patterns
Women appear disproportionately affected.
Several studies indicate female Long COVID patients report:
- More severe insomnia
- Greater sleep fragmentation
- Higher fatigue burden
- Increased autonomic symptoms
Potential explanations include:
- Hormonal influences
- Immune response differences
- Autoimmune susceptibility
- Variations in autonomic regulation
Age also influences presentation.
Younger adults more frequently report:
- Insomnia
- Delayed sleep phase
- Circadian disruption
Older adults more commonly experience:
- Sleep apnea worsening
- Fragmented sleep
- Reduced sleep efficiency
Persistence
Longitudinal investigations reveal remarkable persistence.
Sleep abnormalities have been documented:
- 6 months post infection
- 12 months post infection
- 24 months post infection
- Beyond 36 months in some cohorts
A substantial minority demonstrate little spontaneous improvement over time.
This persistence suggests structural or biologic alterations rather than transient psychological reactions.
Physiology of Normal Sleep
To appreciate Long COVID-associated sleep disorders, normal sleep regulation must first be considered.
Sleep emerges through interaction between two major systems:
Homeostatic Sleep Drive
The longer an individual remains awake, the stronger the biologic pressure to sleep.
Key mediators include:
- Adenosine accumulation
- Cytokine signaling
- Metabolic byproducts
Circadian Regulation
The circadian system is controlled by the:
Suprachiasmatic Nucleus (SCN)
located within the hypothalamus.
The SCN synchronizes:
- Melatonin release
- Cortisol secretion
- Body temperature
- Autonomic activity
- Sleep-wake timing
Disruption produces profound physiologic consequences.
Sleep Architecture
Normal sleep cycles consist of:
NREM Stage 1
Transition to sleep.
NREM Stage 2
Light sleep.
NREM Stage 3
Slow-wave sleep.
Critical for:
- Immune function
- Tissue repair
- Growth hormone secretion
- Glymphatic clearance
REM Sleep
Essential for:
- Memory consolidation
- Emotional processing
- Neuroplasticity
Long COVID appears capable of disrupting every component of this architecture.
Pathophysiology
Neuroinflammation
One of the leading mechanisms involves persistent neuroinflammation.
Evidence demonstrates:
- Activated microglia
- Elevated inflammatory cytokines
- Altered astrocyte function
- Blood-brain barrier disruption
within regions responsible for sleep regulation.
Affected structures may include:
- Hypothalamus
- Brainstem
- Basal forebrain
- Thalamus
Inflammatory injury to these areas can profoundly alter sleep-wake control.
Hypothalamic Dysfunction
The hypothalamus serves as a master regulator of:
- Sleep
- Temperature
- Hormones
- Appetite
- Autonomic function
Several studies suggest hypothalamic involvement in Long COVID.
Potential mechanisms include:
- Direct viral invasion
- Microvascular injury
- Autoimmune attack
- Chronic inflammation
Damage may explain simultaneous disturbances involving:
- Sleep
- Fatigue
- Appetite
- Thermoregulation
commonly observed in Long COVID patients.
Autonomic Nervous System Dysfunction
Autonomic dysfunction has emerged as a hallmark of Long COVID.
Manifestations include:
- Postural Orthostatic Tachycardia Syndrome (POTS)
- Orthostatic intolerance
- Heart rate variability abnormalities
- Sympathetic overactivation
Excess sympathetic activity creates physiologic hyperarousal.
Patients frequently describe:
“Exhausted but unable to sleep.”
This paradox represents a classic manifestation of autonomic dysregulation.
HPA Axis Disruption
The hypothalamic-pituitary-adrenal (HPA) axis regulates cortisol secretion.
Several investigations demonstrate abnormal cortisol patterns among Long COVID patients.
Observed abnormalities include:
- Flattened diurnal rhythms
- Reduced morning cortisol
- Impaired stress responses
- Glucocorticoid signaling defects
These alterations disrupt normal sleep initiation and maintenance.
Glymphatic Dysfunction
The glymphatic system removes metabolic waste from the brain during sleep.
This process is particularly active during slow-wave sleep.
Disruption may impair clearance of:
- Inflammatory mediators
- Protein aggregates
- Cellular debris
Reduced glymphatic function could contribute to:
- Brain fog
- Cognitive dysfunction
- Persistent fatigue
commonly reported in Long COVID.
Mitochondrial Dysfunction
Mitochondria provide cellular energy production.
Emerging evidence indicates:
- Reduced ATP generation
- Oxidative stress
- Impaired fatty acid metabolism
in Long COVID patients.
Sleep deprivation further worsens mitochondrial efficiency, potentially creating a vicious cycle:
Poor sleep → mitochondrial dysfunction → fatigue → further sleep disruption.
Patterns of Sleep Disruption in Long COVID
Several distinct phenotypes have emerged.
Insomnia Phenotype
Most common.
Symptoms include:
- Difficulty falling asleep
- Frequent awakenings
- Early awakening
- Non-restorative sleep
Many patients report never returning to pre-COVID sleep quality.
Hypersomnia Phenotype
Others experience excessive sleepiness.
Characteristics include:
- Sleeping 12–16 hours daily
- Unrefreshing sleep
- Difficulty maintaining wakefulness
This pattern resembles post-viral hypersomnolence syndromes described after influenza and Epstein-Barr infection.
Circadian Dysregulation Phenotype
Patients may exhibit:
- Delayed sleep phase
- Reversed sleep cycles
- Irregular sleep timing
suggesting disruption of central circadian control.
Mixed Phenotype
Many individuals alternate between:
- Insomnia
- Hypersomnia
- Fragmented sleep
reflecting dynamic dysfunction of multiple regulatory systems.
Sleep-Disordered Breathing in Long COVID
Among the most clinically important but underrecognized manifestations of Long COVID is the emergence or worsening of sleep-disordered breathing (SDB), particularly obstructive sleep apnea (OSA).
Several studies have reported that individuals with preexisting OSA are disproportionately represented among Long COVID cohorts. More intriguingly, many patients without prior sleep apnea diagnoses develop symptoms suggestive of newly acquired sleep-disordered breathing following SARS-CoV-2 infection.
These symptoms include:
- Loud snoring
- Witnessed apneas
- Nocturnal choking
- Morning headaches
- Severe daytime fatigue
- Cognitive impairment
- Unrefreshing sleep
Because these complaints overlap extensively with Long COVID itself, sleep apnea often remains undiagnosed.
Mechanisms Contributing to Sleep Apnea
Several pathophysiologic mechanisms may contribute.
Weight Gain
Many Long COVID patients experience:
- Reduced activity
- Exercise intolerance
- Metabolic dysregulation
which frequently leads to weight gain.
Increased upper airway adiposity may promote airway collapse during sleep.
Neuromuscular Dysfunction
SARS-CoV-2 may impair neural control of upper airway musculature through:
- Brainstem injury
- Cranial neuropathies
- Autonomic dysfunction
Reduced pharyngeal muscle tone can increase airway obstruction.
Persistent Inflammation
Chronic inflammation may produce:
- Airway edema
- Mucosal swelling
- Increased airway resistance
further worsening sleep-disordered breathing.
Clinical Consequences
Sleep apnea amplifies many hallmark Long COVID symptoms:
- Fatigue
- Brain fog
- Hypertension
- Depression
- Autonomic dysfunction
- Cardiovascular risk
Importantly, untreated sleep apnea may substantially impair recovery from Long COVID.
Many patients attributed all symptoms to PASC only to experience dramatic improvement following recognition and treatment of previously undiagnosed sleep apnea.
REM Sleep Disturbances
Rapid Eye Movement (REM) sleep plays a critical role in:
- Emotional regulation
- Learning
- Memory consolidation
- Synaptic plasticity
Multiple investigations suggest REM sleep abnormalities occur frequently in Long COVID.
Observed changes include:
- Reduced REM duration
- Increased REM fragmentation
- Altered REM latency
- REM behavior disorder-like phenomena
Neuroanatomic Considerations
REM sleep regulation depends heavily upon:
- Pons
- Midbrain
- Hypothalamus
- Limbic structures
Several of these regions demonstrate evidence of inflammatory injury or altered metabolism in neuroimaging studies of Long COVID.
Disruption may impair emotional processing and memory consolidation.
This could partially explain persistent complaints of:
- Anxiety
- Depression
- Cognitive dysfunction
- Emotional instability
frequently observed among Long COVID patients.
Slow-Wave Sleep Impairment
Deep slow-wave sleep (Stage N3) represents the most restorative phase of human sleep.
Functions include:
- Growth hormone secretion
- Cellular repair
- Immune regulation
- Glymphatic clearance
- Memory consolidation
Evidence increasingly suggests Long COVID patients exhibit significant reductions in slow-wave sleep.
Consequences of Reduced Slow-Wave Sleep
Loss of restorative sleep produces widespread physiologic effects.
Impaired Tissue Repair
Growth hormone secretion occurs primarily during slow-wave sleep.
Reduced N3 sleep may impair:
- Muscle recovery
- Connective tissue healing
- Bone remodeling
- Cellular regeneration
Increased Inflammation
Experimental sleep deprivation studies demonstrate:
- Elevated IL-6
- Elevated TNF-α
- Elevated CRP
all biomarkers commonly elevated in Long COVID.
Reduced Immune Function
Slow-wave sleep facilitates:
- T-cell activation
- Immune memory formation
- Antibody production
Its disruption may prolong inflammatory activation and delay recovery.
Sleep and Neurocognitive Dysfunction
One of the defining features of Long COVID is cognitive impairment.
Patients commonly report:
- Brain fog
- Word-finding difficulty
- Memory loss
- Reduced concentration
- Slowed processing speed
Sleep disruption likely contributes significantly to these deficits.
Memory Consolidation
Sleep is essential for transferring information from:
- Short-term memory
- Long-term memory storage
Particularly important are:
- REM sleep
- Slow-wave sleep
Disruption of either phase can impair memory formation.
Executive Function
Studies of chronic insomnia reveal deficits involving:
- Attention
- Planning
- Decision making
- Working memory
These abnormalities closely mirror those observed in Long COVID.
Glymphatic Clearance Failure
The glymphatic system becomes highly active during deep sleep.
Its functions include removal of:
- Metabolic waste
- Neurotoxic proteins
- Inflammatory mediators
Reduced glymphatic clearance may contribute to persistent cognitive symptoms.
Sleep and Fatigue
Fatigue remains among the most disabling symptoms of Long COVID.
Unlike ordinary tiredness, Long COVID fatigue often exhibits characteristics resembling:
- Myalgic Encephalomyelitis (ME/CFS)
- Post-viral fatigue syndrome
Sleep abnormalities appear intimately linked to this phenomenon.
The Fatigue-Sleep Cycle
Poor sleep leads to:
- Reduced energy production
- Increased inflammation
- Autonomic dysregulation
These changes increase fatigue.
Fatigue then promotes:
- Daytime napping
- Reduced activity
- Circadian disruption
which further worsens sleep.
This self-perpetuating cycle can persist for years.
Sleep and Autonomic Dysfunction
Dysautonomia affects a substantial proportion of Long COVID patients.
Common manifestations include:
- Orthostatic intolerance
- POTS
- Palpitations
- Tachycardia
- Temperature dysregulation
Sleep disturbances both result from and contribute to autonomic dysfunction.
Sympathetic Overactivation
Many patients exhibit:
- Elevated nighttime heart rates
- Excess catecholamine activity
- Reduced parasympathetic tone
The nervous system remains trapped in a physiologic state of hypervigilance.
Patients often describe:
“My body feels exhausted but my nervous system refuses to shut off.”
Heart Rate Variability
Heart rate variability (HRV) reflects autonomic balance.
Studies frequently demonstrate:
- Reduced HRV
- Increased sympathetic dominance
in Long COVID.
Sleep disruption further worsens these abnormalities.
Sleep and Immune Function
The immune system and sleep are inseparably linked.
Sleep influences:
- Cytokine production
- T-cell activity
- Antibody generation
- Inflammatory resolution
Inflammatory Amplification
Even modest sleep deprivation increases:
- IL-1β
- IL-6
- TNF-α
- CRP
These inflammatory mediators are implicated in Long COVID pathogenesis.
Thus, sleep loss may perpetuate chronic inflammation.
Autoimmunity
Emerging evidence suggests autoimmune mechanisms contribute to Long COVID.
Sleep disruption may worsen autoimmunity through:
- Enhanced antigen presentation
- Altered T-cell regulation
- Reduced regulatory T-cell activity
These changes may sustain pathogenic immune responses.
Sleep and Endocrine Dysfunction
Long COVID affects multiple hormonal systems.
Reported abnormalities include:
- Cortisol dysregulation
- Thyroid dysfunction
- Gonadal hormone abnormalities
- Growth hormone alterations
Sleep disruption can exacerbate each of these disturbances.
Cortisol
Normal cortisol rhythms promote:
- Morning wakefulness
- Nighttime sleep initiation
Flattened cortisol curves have been documented in Long COVID.
Abnormal cortisol signaling may contribute to:
- Fatigue
- Insomnia
- Brain fog
Growth Hormone
Growth hormone secretion depends largely upon deep sleep.
Reduced slow-wave sleep may impair:
- Tissue repair
- Muscle recovery
- Cellular regeneration
potentially slowing recovery.
Sleep and Cardiovascular Health
Sleep abnormalities are well-established cardiovascular risk factors.
Long COVID already appears associated with increased risk for:
- Arrhythmias
- Endothelial dysfunction
- Hypertension
- Coronary disease
Sleep disruption may amplify these risks.
Endothelial Dysfunction
Sleep deprivation impairs endothelial function through:
- Oxidative stress
- Inflammation
- Nitric oxide dysregulation
These mechanisms overlap substantially with Long COVID vascular pathology.
Atrial Fibrillation
Emerging evidence suggests increased rates of atrial fibrillation following COVID-19 infection.
Poor sleep and untreated sleep apnea further elevate risk.
For Long COVID patients with atrial fibrillation, sleep evaluation may be particularly important.
Sleep and Metabolic Health
Long COVID is increasingly recognized as a metabolic disorder.
Reported abnormalities include:
- Insulin resistance
- Glucose dysregulation
- Altered lipid metabolism
- Weight gain
Sleep disruption contributes directly to these processes.
Insulin Resistance
Even short-term sleep restriction reduces insulin sensitivity.
Potential mechanisms include:
- Cortisol elevation
- Sympathetic activation
- Inflammatory cytokines
Persistent sleep abnormalities may therefore worsen metabolic dysfunction.
Obesity
Poor sleep alters appetite-regulating hormones:
- Increased ghrelin
- Reduced leptin
These changes promote:
- Increased caloric intake
- Weight gain
which may further worsen sleep-disordered breathing.
Psychiatric Consequences
Psychiatric symptoms frequently accompany Long COVID.
Common manifestations include:
- Anxiety
- Depression
- Panic attacks
- Emotional lability
Sleep disruption likely serves as both cause and consequence.
Depression
Insomnia is among the strongest predictors of major depression.
Long COVID patients experiencing chronic insomnia demonstrate significantly higher rates of depressive symptoms.
Anxiety
Sleep fragmentation enhances:
- Amygdala reactivity
- Fear processing
- Stress responses
These mechanisms may contribute to persistent anxiety disorders.
Impact on Daily Function
Sleep disorders profoundly affect daily life.
Patients frequently report inability to:
- Return to work
- Maintain employment
- Drive safely
- Exercise
- Participate socially
For many individuals, sleep dysfunction becomes a major determinant of disability.
Occupational Consequences
Sleep impairment contributes to:
- Reduced productivity
- Increased absenteeism
- Cognitive errors
- Occupational injuries
Healthcare workers, pilots, drivers, and professionals requiring sustained concentration may experience particularly severe consequences.
Quality of Life
Studies consistently demonstrate strong correlations between sleep quality and:
- Functional status
- Emotional well-being
- Cognitive performance
- Overall health perception
Sleep may therefore represent one of the most modifiable determinants of Long COVID quality of life.
Part III: Diagnostic Evaluation, Therapeutic Approaches, Prognosis, and Future Directions
Diagnostic Evaluation
Sleep disturbances in Long COVID present unique diagnostic challenges because symptoms frequently overlap with fatigue, autonomic dysfunction, depression, anxiety, endocrine abnormalities, cardiopulmonary disease, and medication effects. Consequently, evaluation requires a comprehensive and multidisciplinary approach.
The diagnostic objective is not merely identification of sleep disruption but determination of whether sleep pathology serves as a primary driver, secondary consequence, or perpetuating factor in the patient’s overall symptom burden.
Clinical History
Evaluation begins with a detailed sleep history.
Key elements include:
- Sleep onset latency
- Number of nocturnal awakenings
- Wake after sleep onset
- Total sleep duration
- Sleep quality
- Daytime sleepiness
- Fatigue severity
- Napping behavior
- Snoring
- Witnessed apnea
- Restless legs symptoms
- Circadian timing
Particular attention should be directed toward pre-COVID sleep characteristics because many patients can identify a clear temporal relationship between SARS-CoV-2 infection and symptom onset.
Several cohort studies suggest that individuals with preexisting sleep disorders exhibit increased risk of developing Long COVID.[1,2]
Standardized Assessment Instruments
Validated instruments improve diagnostic consistency.
Frequently utilized tools include:
Pittsburgh Sleep Quality Index (PSQI)
Measures subjective sleep quality.
Insomnia Severity Index (ISI)
Quantifies insomnia symptoms and treatment response.
Epworth Sleepiness Scale (ESS)
Evaluates excessive daytime sleepiness.
Functional Outcomes of Sleep Questionnaire (FOSQ)
Measures functional impairment associated with poor sleep.
PROMIS Sleep Disturbance Scale
Increasingly used in Long COVID research cohorts.[3]
Physical Examination
Physical examination should include assessment of:
- Body mass index
- Neck circumference
- Oropharyngeal anatomy
- Blood pressure
- Orthostatic vital signs
- Neurologic status
- Cardiopulmonary function
Signs of dysautonomia are particularly common among Long COVID patients with sleep complaints.[4]
Laboratory Evaluation
Routine laboratory testing helps identify potentially reversible contributors.
Recommended studies include:
- Complete blood count
- Comprehensive metabolic panel
- Thyroid function studies
- Ferritin
- Iron studies
- Vitamin B12
- Vitamin D
- Morning cortisol
- HbA1c
- Inflammatory biomarkers
Selected patients may benefit from:
- ACTH
- Growth hormone axis assessment
- Sex hormone evaluation
Polysomnography
Overnight polysomnography remains the gold standard for evaluating sleep architecture.
Parameters assessed include:
- Sleep stages
- Respiratory events
- Oxygen saturation
- Limb movements
- Heart rhythm
- REM characteristics
Several Long COVID studies have demonstrated:
- Reduced sleep efficiency
- Increased sleep fragmentation
- Reduced slow-wave sleep
- Altered REM architecture
- Increased arousal indices.[5,6]
These findings support biologic disruption rather than simple psychological insomnia.
Actigraphy and Wearable Monitoring
Wearable technologies have emerged as important research tools.
Actigraphy permits prolonged assessment of:
- Sleep duration
- Sleep timing
- Circadian patterns
- Activity levels
Several Long COVID investigations have identified persistent circadian disruption months following infection.[7]
Continuous monitoring frequently reveals patterns not appreciated during office visits.
Differential Diagnosis
The differential diagnosis is broad.
Potential contributors include:
Primary Insomnia
Existing prior to infection.
Sleep Apnea
Either preexisting or newly developed.
Restless Legs Syndrome
Often associated with iron deficiency or neurologic dysfunction.
Circadian Rhythm Disorders
Frequently observed after COVID infection.
Depression
May produce both insomnia and hypersomnia.
Medication Effects
Common offenders include:
- Corticosteroids
- Stimulants
- Antidepressants
- Beta agonists
Endocrine Disorders
Including thyroid disease and adrenal dysfunction.
Treatment
Because Long COVID-associated sleep disorders appear multifactorial, treatment generally requires multimodal intervention.
Sleep Hygiene
Although rarely sufficient as monotherapy, optimization remains foundational.
Recommendations include:
- Fixed wake time
- Reduced evening light exposure
- Elimination of late caffeine
- Temperature optimization
- Consistent sleep schedule
- Avoidance of excessive daytime naps
These measures help stabilize circadian rhythms.[8]
Cognitive Behavioral Therapy for Insomnia (CBT-I)
CBT-I remains the first-line treatment for chronic insomnia.
Components include:
- Stimulus control
- Sleep restriction
- Cognitive restructuring
- Relaxation training
Multiple randomized trials have demonstrated efficacy superior to pharmacologic therapy for chronic insomnia.[9]
Long COVID patients appear to benefit similarly.
Melatonin
Melatonin deserves special attention in Long COVID.
Beyond circadian regulation, melatonin possesses:
- Anti-inflammatory effects
- Antioxidant activity
- Mitochondrial protection
- Immune modulation
Several investigators have proposed melatonin as a potentially disease-modifying intervention in Long COVID.[10,11]
Typical doses range from 0.5 mg to 10 mg nightly depending upon therapeutic goals.
Orexin Antagonists
The orexin system plays a critical role in wakefulness.
Recently approved dual orexin receptor antagonists include:
- Suvorexant
- Lemborexant
- Daridorexant
These agents may be particularly useful in Long COVID patients exhibiting autonomic hyperarousal.
Unlike benzodiazepines, they preserve more normal sleep architecture.[12]
Antihistamines
Histamine functions as a wake-promoting neurotransmitter.
Interest in antihistamines has grown because mast-cell activation has been proposed as a contributor to Long COVID pathology.
Agents commonly utilized include:
- Hydroxyzine
- Diphenhydramine
- Doxylamine
Although evidence remains limited, some patients report meaningful symptomatic improvement.[13]
Treatment of Sleep Apnea
Sleep apnea treatment is particularly important because untreated disease may perpetuate:
- Fatigue
- Cognitive dysfunction
- Cardiovascular risk
- Autonomic instability
Primary therapies include:
- CPAP
- AutoPAP
- Weight management
- Positional therapy
- Oral appliances
Several Long COVID cohorts have demonstrated substantial improvement in fatigue after sleep apnea treatment.[14]
Management of Dysautonomia
Because autonomic dysfunction contributes significantly to sleep disruption, treatment may improve both sleep and daytime symptoms.
Approaches include:
- Increased fluid intake
- Salt supplementation
- Compression garments
- Exercise rehabilitation
- Beta blockers
- Ivabradine
- Midodrine
Improved autonomic regulation often improves sleep quality.[15]
Emerging Therapies
Several experimental interventions are currently under investigation.
These include:
Low-Dose Naltrexone (LDN)
Potential reduction of neuroinflammation and microglial activation.
Vagus Nerve Stimulation
Potential restoration of autonomic balance.
Stellate Ganglion Block
Proposed reduction of sympathetic overactivation.
Photobiomodulation
Potential mitochondrial support.
Hyperbaric Oxygen Therapy
Potential improvement in neurocognitive function and sleep quality.
Evidence remains preliminary but promising.[16–18]
Long-Term Prognosis
Long-term prognosis remains incompletely understood.
Several longitudinal studies suggest gradual improvement in sleep quality over time, particularly during the first two years after infection.[19]
However, a significant minority remain symptomatic beyond three years.
Factors Associated with Better Outcomes
Improved prognosis appears associated with:
- Younger age
- Vaccination
- Mild acute illness
- Early intervention
- Absence of major comorbidities
Factors Associated with Persistent Symptoms
Poorer outcomes appear associated with:
- Female sex
- Severe acute illness
- Preexisting sleep disorders
- Dysautonomia
- Multiple organ involvement
- Psychiatric comorbidity
Future Directions
The next decade of Long COVID research will likely focus on several critical questions.
Is Sleep Disturbance a Cause or Consequence?
Current evidence increasingly suggests both.
Can Sleep Restoration Accelerate Recovery?
Interventional studies remain urgently needed.
Are Distinct Sleep Phenotypes Present?
Emerging evidence suggests multiple biologically distinct subgroups.
Can Sleep Biomarkers Predict Outcome?
Identification of predictive markers could dramatically improve patient stratification.
Does Sleep Represent a Therapeutic Target?
Perhaps the most important question.
If sleep dysfunction perpetuates inflammation, autonomic instability, and impaired tissue repair, treatment could modify disease trajectory rather than merely alleviate symptoms.
Conclusion
Sleep disorders have emerged as one of the most prevalent, persistent, and biologically significant manifestations of Long COVID. Far from representing a secondary symptom, sleep disruption appears deeply integrated into the pathophysiologic framework of Post-Acute Sequelae of SARS-CoV-2 Infection.
Current evidence implicates neuroinflammation, hypothalamic injury, autonomic dysfunction, mitochondrial impairment, endocrine dysregulation, and glymphatic failure as interacting mechanisms disrupting normal sleep architecture. In turn, disturbed sleep amplifies inflammation, cognitive dysfunction, fatigue, autonomic instability, and impaired healing.
The resulting bidirectional relationship may represent one of the central self-perpetuating cycles sustaining Long COVID.
Recognition of sleep pathology therefore carries implications extending beyond symptom management. Sleep assessment should become a routine component of Long COVID evaluation, while restoration of healthy sleep may ultimately emerge as one of the most important therapeutic targets in this complex and evolving disorder.
Molecular Mechanisms Linking Long COVID and Sleep Dysfunction
Neuroimmune Interactions
One of the most important developments in Long COVID research has been recognition of the intimate relationship between sleep regulation and immune function. Sleep is not merely a neurologic phenomenon but rather a complex biologic process regulated by bidirectional communication between the central nervous system and the immune system.
Acute infection normally induces adaptive alterations in sleep architecture. During viral illnesses, increased slow-wave sleep and somnolence may facilitate immune surveillance, antibody production, and tissue repair. However, when inflammatory signaling becomes chronic, the same pathways that initially promote recovery may become maladaptive.[20]
Persistent elevations of inflammatory mediators including interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and numerous chemokines have been documented in subsets of Long COVID patients.[21,22]
These cytokines directly influence sleep-regulating structures within the:
- Hypothalamus
- Basal forebrain
- Brainstem reticular activating system
- Thalamus
Chronic exposure may alter neuronal firing patterns and neurotransmitter balance, contributing to fragmented sleep, excessive daytime sleepiness, and non-restorative sleep.[23]
Microglial Activation
Microglia serve as the resident immune cells of the central nervous system.
Under physiologic conditions microglia:
- Remove cellular debris
- Support synaptic remodeling
- Participate in learning and memory
- Regulate inflammatory responses
Persistent activation has emerged as one of the leading hypotheses explaining Long COVID neurologic symptoms.
Activated microglia release:
- IL-1β
- TNF-α
- Reactive oxygen species
- Nitric oxide
These substances may interfere with neuronal networks responsible for maintaining normal sleep architecture.[24]
Positron emission tomography studies have demonstrated evidence of persistent neuroinflammation in several brain regions implicated in sleep regulation, including the thalamus and brainstem.[25]
This observation provides a biologically plausible explanation for persistent insomnia and hypersomnolence occurring months after infection.
Astrocyte Dysfunction
Astrocytes play essential roles in:
- Neurotransmitter recycling
- Blood-brain barrier maintenance
- Energy metabolism
- Glymphatic clearance
Recent evidence suggests astrocytic dysfunction may contribute significantly to Long COVID pathology.[26]
Sleep deprivation itself impairs astrocyte function, while astrocyte injury further degrades sleep quality.
This reciprocal interaction may help explain why many patients experience progressive symptom amplification despite apparent resolution of acute infection.
Neurotransmitter Dysregulation
Several neurotransmitter systems implicated in sleep regulation appear altered in Long COVID.
Serotonin
Serotonin influences:
- Sleep onset
- Mood
- Pain perception
- Cognitive processing
Recent investigations suggest reduced serotonin bioavailability may occur following SARS-CoV-2 infection due to altered tryptophan metabolism and persistent inflammatory signaling.[27]
Reduced serotonin may contribute simultaneously to:
- Insomnia
- Depression
- Fatigue
- Cognitive dysfunction
Dopamine
Dopaminergic pathways regulate:
- Wakefulness
- Motivation
- Executive function
- Motor activity
Neuroinflammatory injury affecting dopamine pathways may contribute to:
- Hypersomnolence
- Fatigue
- Reduced motivation
- Cognitive slowing
commonly reported among Long COVID patients.[28]
Orexin (Hypocretin)
Orexin-producing neurons located in the lateral hypothalamus play a critical role in wakefulness maintenance.
Disruption of orexin signaling has been proposed as a mechanism underlying:
- Excessive daytime sleepiness
- Hypersomnia
- Fatigue syndromes
Several investigators have suggested that inflammatory injury involving hypothalamic nuclei may impair orexin signaling in Long COVID.[29]
Mitochondrial Dysfunction and Sleep
Mitochondrial dysfunction has become one of the most extensively investigated mechanisms in Long COVID.
Reported abnormalities include:
- Reduced oxidative phosphorylation
- Impaired ATP production
- Increased oxidative stress
- Altered fatty-acid metabolism
Sleep deprivation independently produces many of the same abnormalities.[30]
Experimental studies demonstrate that even modest reductions in sleep duration can impair mitochondrial respiration and increase reactive oxygen species production.
The convergence of Long COVID-associated mitochondrial dysfunction and chronic sleep disruption may therefore produce a synergistic reduction in cellular energy availability.
This mechanism provides a compelling explanation for profound fatigue experienced by many patients.
Endothelial Dysfunction and Cerebral Perfusion
SARS-CoV-2 infection can produce widespread endothelial injury.
Consequences include:
- Reduced nitric oxide availability
- Microvascular dysfunction
- Impaired cerebral blood flow
- Altered oxygen delivery
Sleep itself depends upon precisely regulated cerebral perfusion.
Several neuroimaging studies have demonstrated reduced regional blood flow within:
- Frontal cortex
- Brainstem
- Temporal lobes
- Basal ganglia
among Long COVID patients.[31]
These abnormalities may contribute simultaneously to sleep dysfunction and neurocognitive impairment.
Persistent Viral Antigen Hypothesis
An area of intense investigation involves persistence of viral proteins or viral RNA fragments following acute infection.
Multiple studies have identified SARS-CoV-2 antigens within:
- Gastrointestinal tissues
- Lymphoid tissues
- Circulating monocytes
months after acute illness.[32]
Persistent antigen exposure could theoretically maintain chronic immune activation.
Continued cytokine production may subsequently disrupt sleep-regulating neural circuits.
Although definitive proof remains lacking, this hypothesis remains one of the most biologically plausible explanations for prolonged symptom persistence.
Autoimmunity
Evidence increasingly supports autoimmune contributions to Long COVID.
Investigators have identified autoantibodies directed against:
- G-protein coupled receptors
- Autonomic nervous system targets
- Endothelial structures
- Neural antigens
in subsets of patients.[33]
Autoimmune injury involving hypothalamic or brainstem structures could theoretically impair normal sleep regulation.
Similar mechanisms have been implicated in narcolepsy and other sleep disorders.
The Glymphatic Failure Hypothesis
The glymphatic system functions as a waste-clearance network within the brain.
During slow-wave sleep, cerebrospinal fluid flow increases dramatically, facilitating removal of:
- Metabolic byproducts
- Protein aggregates
- Inflammatory mediators
Reduction of slow-wave sleep may impair this process.[34]
Impaired clearance could permit accumulation of inflammatory molecules, further worsening neuroinflammation and sleep disruption.
A vicious cycle may therefore develop:
Neuroinflammation → Poor Sleep → Reduced Glymphatic Clearance → More Neuroinflammation.
This model has gained increasing support as a unifying explanation for persistent cognitive dysfunction and fatigue.
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