Anxiety and Insomnia Comorbidity: Bidirectional Relationship, Shared Neurobiology, and Integrated Treatment Approaches

Anxiety disorders and insomnia disorder co-occur at rates far exceeding what chance alone would predict. This comorbidity is not incidental — it reflects deeply intertwined neurobiological systems, shared cognitive-behavioral maintaining factors, and a bidirectional causal relationship in which each condition amplifies the other. Clinicians who treat either condition in isolation, without addressing the other, routinely encounter treatment resistance and partial remission. Understanding the mechanistic intersection of these two conditions is therefore not an academic exercise but a clinical imperative.

The DSM-5-TR defines insomnia disorder as dissatisfaction with sleep quantity or quality associated with difficulty initiating sleep, maintaining sleep, or early-morning awakening, occurring at least three nights per week for at least three months, causing clinically significant distress or functional impairment. Critically, the DSM-5-TR moved away from the older distinction between "primary" and "secondary" insomnia, recognizing that insomnia co-occurring with another mental disorder warrants independent clinical attention and is not merely a symptom to be subsumed. This nosological shift has profound treatment implications: insomnia comorbid with anxiety is a disorder in its own right, not an expected byproduct that will resolve once anxiety is managed.

Anxiety disorders — including generalized anxiety disorder (GAD), panic disorder, social anxiety disorder, and specific phobias — collectively represent the most prevalent class of mental disorders worldwide, with a 12-month prevalence of approximately 19.1% in U.S. adults (NIMH). Insomnia disorder affects approximately 6–10% of the general population when using strict DSM-5-TR criteria, though insomnia symptoms (not meeting full diagnostic thresholds) affect 30–35% of adults. When these conditions converge in a single patient, the resulting clinical picture is qualitatively different from either alone — marked by greater functional impairment, higher healthcare utilization, elevated suicide risk, and more refractory treatment courses.

The bidirectional epidemiological relationship between anxiety and insomnia is among the strongest in psychiatric comorbidity research. The data are striking from both directions:

Insomnia Among Individuals with Anxiety Disorders

Studies consistently show that 50–70% of individuals with a diagnosed anxiety disorder report clinically significant insomnia symptoms, with rates varying by anxiety subtype. Generalized anxiety disorder shows the highest comorbidity — approximately 60–70% of individuals with GAD meet criteria for comorbid insomnia disorder, likely because the core feature of GAD (persistent, uncontrollable worry) directly interferes with the cognitive de-arousal necessary for sleep onset. Panic disorder shows comorbidity rates of approximately 50–60%, partly driven by nocturnal panic attacks, which occur in an estimated 44–71% of panic disorder patients and profoundly disrupt sleep continuity. Social anxiety disorder and specific phobias show somewhat lower but still elevated rates of 40–50%.

Anxiety Among Individuals with Insomnia

Conversely, approximately 36–42% of individuals with insomnia disorder meet criteria for a comorbid anxiety disorder, according to data from the large-scale epidemiological studies including the National Comorbidity Survey Replication (NCS-R). A meta-analysis by Baglioni and colleagues (2011) in the Journal of Affective Disorders found that individuals with insomnia had a two-fold increased risk of developing an anxiety disorder compared to good sleepers (odds ratio ≈ 2.0). This prospective risk is clinically significant: insomnia is not just a correlate of anxiety but a robust, independent predictor of new-onset anxiety.

The Temporal Relationship

Longitudinal data reveal that the temporal sequence is genuinely bidirectional, though with an asymmetry. Insomnia more consistently precedes the development of anxiety than the reverse. A landmark meta-analysis by Hertenstein and colleagues (2019) pooled data from 34 prospective cohort studies and found that non-depressed individuals with insomnia had a significantly elevated risk of developing anxiety disorders (relative risk = 3.23, 95% CI: 1.52–6.85). Meanwhile, anxiety disorders also predict the development of chronic insomnia, with prospective studies showing that GAD in particular increases the risk of persistent insomnia at 1–3 year follow-up by approximately two-fold. This bidirectional risk creates a vicious cycle: insomnia increases vulnerability to anxiety, which in turn perpetuates and worsens insomnia.

The high comorbidity between anxiety and insomnia is grounded in overlapping neurocircuitry, shared neurotransmitter dysregulation, and common neuroendocrine abnormalities. Several specific mechanisms have been identified:

Hyperarousal: The Central Shared Mechanism

The hyperarousal model, most comprehensively articulated by Riemann and colleagues (2010), posits that chronic insomnia is fundamentally a disorder of excessive 24-hour arousal rather than a nighttime-only phenomenon. This maps directly onto the core neurobiology of anxiety, which is similarly characterized by tonic hyperarousal. Physiological markers shared by both conditions include elevated whole-brain metabolic rate during NREM sleep (demonstrated via FDG-PET imaging by Nofzinger et al., 2004), increased high-frequency EEG beta power during sleep onset, elevated heart rate variability reflecting sympathetic dominance, and increased cortisol secretion across the circadian cycle.

HPA Axis Dysregulation

Both anxiety disorders and insomnia are associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Chronic insomnia is associated with elevated evening cortisol levels — a flattening of the normal cortisol diurnal rhythm — which mirrors findings in GAD and panic disorder. Corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus project to brainstem arousal centers including the locus coeruleus (LC), creating a direct pathway through which stress-hormone activation promotes wakefulness and suppresses sleep. This CRH-mediated activation also drives anxious apprehension, linking the two conditions at the molecular level.

Locus Coeruleus-Norepinephrine System

The locus coeruleus (LC), the brain's primary noradrenergic nucleus, plays a central role in both conditions. LC neurons must reduce their firing rate substantially for sleep onset to occur — LC is virtually silent during REM sleep. In anxiety disorders, LC firing is tonically elevated, driven by amygdala input and CRH signaling. This elevated noradrenergic tone directly opposes the neurophysiological prerequisites for sleep, explaining why anxious patients report difficulty with sleep onset (the LC won't "turn off") and show increased arousals from sleep. Functional imaging studies demonstrate that patients with both insomnia and anxiety show greater amygdala-LC coupling than those with either condition alone.

GABAergic Deficiency

Gamma-aminobutyric acid (GABA) is the brain's primary inhibitory neurotransmitter and is fundamental to both anxiety modulation and sleep generation. Magnetic resonance spectroscopy (MRS) studies have found reduced GABA levels in the occipital cortex and anterior cingulate cortex of patients with insomnia (Winkelman et al., 2008), and similar GABAergic deficits are found in anxiety disorders. The ventrolateral preoptic area (VLPO) of the hypothalamus — the brain's "sleep switch" — depends on GABAergic inhibition of wake-promoting centers including the tuberomammillary nucleus, lateral hypothalamus, and dorsal raphe. Insufficient GABAergic tone simultaneously impairs sleep generation and releases anxiety-related circuits from inhibitory control.

Amygdala Reactivity and Prefrontal Regulation

Sleep deprivation studies by Walker and colleagues have demonstrated that even a single night of total sleep deprivation increases amygdala reactivity to negative emotional stimuli by approximately 60%, while simultaneously reducing functional connectivity between the amygdala and the medial prefrontal cortex (mPFC), which normally provides top-down emotional regulation. This creates a neurobiological pathway by which poor sleep directly amplifies anxiety: sleep loss erodes the prefrontal "brake" on amygdala-driven fear responses. In patients with comorbid insomnia and anxiety, this mechanism creates a self-perpetuating cycle — anxiety impairs sleep, and impaired sleep further disinhibits the amygdala, amplifying anxiety.

Orexin/Hypocretin System

Emerging research implicates the orexin (hypocretin) system as a shared mediator. Orexin neurons in the lateral hypothalamus promote wakefulness and are activated by stress. Elevated orexin signaling has been observed in animal models of anxiety, and the success of dual orexin receptor antagonists (DORAs) like suvorexant and lemborexant in treating insomnia — with preliminary evidence suggesting anxiolytic effects — supports the relevance of this system to both conditions.

When anxiety and insomnia co-occur, the resulting clinical presentation differs meaningfully from either condition in isolation. Recognizing these differences is essential for accurate assessment and treatment planning.

Greater Severity and Functional Impairment

Patients with comorbid anxiety and insomnia consistently demonstrate greater functional impairment than those with either condition alone. Data from the WHO World Mental Health Surveys indicate that comorbid insomnia with any anxiety disorder is associated with a 1.5 to 2.5-fold increase in disability days per month compared to anxiety without insomnia. Workplace productivity losses are particularly pronounced — presenteeism (being at work but functioning poorly) may be more impactful than absenteeism in this population.

Altered Cognitive Profile

The cognitive distortions characteristic of each condition compound each other. Anxious patients with insomnia develop anxiety about sleep itself — a conditioned cognitive-emotional response in which the bed, bedroom, and bedtime become conditioned stimuli for anxious arousal. This "meta-worry" (worrying about worrying about not sleeping) creates a layered cognitive architecture that is more treatment-resistant than the worry patterns of either disorder alone. Attentional bias studies show that comorbid patients show heightened vigilance to both threat cues and sleep-related cues, indicating dual attentional biases operating simultaneously.

Clinical Vignette: Diagnostic Complexity

A 34-year-old woman presents with a chief complaint of "I can't turn my mind off at night." She reports lying awake for 1–2 hours most nights, ruminating about work conflicts and family responsibilities. She describes daytime fatigue, irritability, difficulty concentrating, and muscle tension. She reports that her sleep problems began approximately 6 months ago during a period of increased work stress, but the stress has since resolved and the sleep difficulty persists. She now reports increasing worry about her ability to function at work due to sleep loss and has begun avoiding social engagements because she feels "too tired."

This presentation illustrates the diagnostic challenge: Does this patient have GAD with insomnia as a feature? Insomnia disorder with secondary anxiety about sleep-related consequences? Or both as independent comorbid conditions? The answer has treatment implications. The persistence of insomnia beyond the resolution of the initial stressor, combined with the development of conditioned arousal around sleep, suggests independent insomnia disorder. The generalized worry pattern extending to multiple domains (work, social, functioning) and associated somatic symptoms (muscle tension) suggest GAD. The clinician should diagnose both and treat both.

Increased Suicide Risk

The combination of anxiety and insomnia confers elevated suicide risk that exceeds what would be predicted from either condition alone. Insomnia has been identified as an independent risk factor for suicidal ideation and suicide attempts even after controlling for depression and anxiety (Pigeon et al., 2012). When comorbid with anxiety, the agitated, ruminative, hopeless quality of sleepless nights may create a particularly dangerous window of vulnerability, especially in the pre-dawn hours when cortisol nadirs and social isolation converge.

Comorbidity between anxiety and insomnia significantly affects treatment response. Several key principles emerge from the literature:

Insomnia Reduces Response to Anxiety Treatment

Patients with anxiety disorders who have comorbid insomnia show attenuated response to first-line anxiety treatments. In CBT for anxiety disorders, comorbid insomnia predicts smaller effect sizes and higher dropout rates. In pharmacotherapy, the STAR*D trial and subsequent analyses demonstrate that baseline insomnia predicts poorer antidepressant response (relevant because SSRIs are first-line for both depression and anxiety). Manber and colleagues (2008) found that persistent insomnia during acute-phase treatment of depression significantly predicted non-remission — findings that likely extend to anxiety treatment given shared mechanisms.

Pharmacological Considerations

The comorbidity influences medication selection in specific ways:

• SSRIs and SNRIs: First-line for anxiety disorders, but can initially worsen insomnia in 15–25% of patients due to serotonergic activation. This early-treatment insomnia exacerbation may drive dropout in anxious patients who are already sleep-deprived and distressed. Clinicians often co-prescribe short-term sleep aids during SSRI titration.
• Benzodiazepines: Effective for both conditions acutely (addressing anxiety and promoting sleep via GABA-A receptor potentiation), but carry substantial risks including tolerance, dependence, rebound insomnia, and cognitive impairment. The American Academy of Sleep Medicine (AASM) and APA guidelines recommend against long-term benzodiazepine use for insomnia. NNT for short-term insomnia improvement with benzodiazepines is approximately 4–6, but this must be weighed against the NNH for adverse events.
• DORAs (suvorexant, lemborexant): Promote sleep by blocking orexin-mediated wakefulness. Emerging evidence suggests benefits for comorbid insomnia-anxiety given the role of orexin in both arousal and stress. Lemborexant has shown efficacy in improving both sleep onset and sleep maintenance insomnia with a generally favorable side-effect profile, and post-hoc analyses suggest possible anxiolytic properties, though this requires confirmatory research.
• Gabapentin and pregabalin: Pregabalin is approved for GAD in Europe (though not in the United States) and has demonstrated sleep-improving effects, making it a potentially useful option for comorbid presentations. Effect sizes for GAD are moderate (Cohen's d ≈ 0.35–0.50), and it significantly improves sleep quality indices in GAD patients.
• Trazodone: Widely used off-label for insomnia at low doses (25–100 mg), trazodone acts via 5-HT2A antagonism and histamine H1 blockade to promote sleep. It is not a first-line anxiolytic, but it can address the insomnia component while SSRIs address anxiety, making it a common adjunctive choice.

Psychotherapy Considerations

Standard CBT for anxiety disorders does not include sleep-specific interventions such as stimulus control and sleep restriction — the core behavioral components of CBT for insomnia (CBT-I). Similarly, standard CBT-I does not typically address generalized worry, safety behaviors, or anxiety-specific cognitive distortions beyond sleep-related worry. This gap in coverage explains why treating only one condition often leaves the other undertreated. The emergence of transdiagnostic and integrated protocols (discussed below) aims to close this gap.

A central clinical question is whether anxiety and insomnia should be treated simultaneously with an integrated protocol, sequentially (treating one first), or in parallel (concurrent but independent treatments). The evidence increasingly favors integrated or insomnia-first approaches.

CBT-I as a "Transdiagnostic" Intervention

The most compelling evidence comes from trials examining the effect of CBT-I on comorbid conditions. A landmark randomized controlled trial by Manber et al. (2008) demonstrated that adding CBT-I to antidepressant treatment for patients with comorbid major depression and insomnia nearly doubled remission rates for depression (61.5% with combined treatment vs. 33.3% with antidepressant plus sleep hygiene control). While this study focused on depression, subsequent research has extended findings to anxiety.

The Improving Access to Psychological Therapies (IAPT) dataset from the UK's National Health Service, analyzed by Freeman and colleagues, found that treating insomnia with CBT-I produced significant reductions in anxiety symptoms, with effect sizes in the moderate range (Cohen's d ≈ 0.35–0.45 for anxiety outcomes). The Oxford OASIS trial (Freeman et al., 2017), a large randomized controlled trial of digital CBT-I (delivered via the Sleepio program) in university students, demonstrated that CBT-I not only improved insomnia (between-group effect size d = 1.11) but also produced significant improvements in paranoia and anxiety, with small-to-moderate effect sizes. These findings support the conceptualization of insomnia as a causal contributor to anxiety rather than merely a symptom — and suggest that resolving insomnia can have therapeutic "downstream" effects on anxiety.

The "Insomnia First" Approach

Given the evidence that untreated insomnia undermines anxiety treatment outcomes, some clinical researchers advocate treating insomnia first or at least concurrently from the outset. The rationale is threefold: (1) improved sleep restores prefrontal-amygdala regulation, reducing emotional reactivity; (2) sleep improvement provides an early treatment "win" that enhances self-efficacy and treatment engagement; and (3) CBT-I has a relatively rapid onset of action (significant improvement typically within 4–8 sessions over 6–8 weeks), meaning it can quickly create a foundation for subsequent anxiety-focused work.

Transdiagnostic CBT Protocols

Harvey's Transdiagnostic Sleep and Circadian Intervention (TranS-C) represents an effort to develop a unified treatment addressing sleep and mental health comorbidities simultaneously. The protocol integrates core CBT-I components (stimulus control, sleep restriction, cognitive restructuring of sleep-related beliefs) with modules addressing emotion regulation, worry management, and behavioral activation. Preliminary data suggest that TranS-C produces larger effects on comorbid psychiatric symptoms than standard CBT-I alone, though large-scale comparative effectiveness trials are still needed.

Additionally, the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (Barlow et al.) addresses anxiety, depression, and related conditions through a focus on shared mechanisms including neuroticism, emotional avoidance, and maladaptive emotion regulation strategies. While not specifically designed for insomnia, its emphasis on reducing experiential avoidance and increasing distress tolerance has theoretical relevance for the hyperarousal and sleep-effort paradoxes central to insomnia.

Sequential Treatment: When It's Indicated

Sequential treatment may be preferred when one condition is clearly dominant in severity or when the patient's capacity for simultaneous treatment engagement is limited. If a patient presents with severe panic disorder with nocturnal panic attacks and moderate insomnia, stabilizing panic symptoms first (via SSRI and panic-focused CBT) may be necessary before the patient can tolerate sleep restriction therapy, which initially increases sleep pressure and may transiently worsen anxiety and arousal in sensitive patients.

Given the high bidirectional comorbidity rates, systematic screening for the partner condition should be standard clinical practice whenever anxiety or insomnia is identified.

When Anxiety Is Diagnosed: Screen for Insomnia

Every patient presenting with an anxiety disorder should be screened for insomnia using a validated instrument. The Insomnia Severity Index (ISI) is a 7-item self-report measure with excellent psychometric properties (Cronbach's α = 0.90; sensitivity and specificity for insomnia disorder ≈ 82–86% at a cutoff of 10–14, depending on the population). The ISI takes less than 3 minutes to administer and is freely available for clinical use. The Pittsburgh Sleep Quality Index (PSQI) provides a broader assessment of sleep quality and disturbance patterns. A PSQI global score > 5 identifies poor sleepers with a sensitivity of 89.6% and specificity of 86.5%.

Clinicians should also ask specifically about:

• Time to fall asleep (sleep onset latency > 30 minutes is clinically significant)
• Number and duration of awakenings per night
• Nocturnal panic episodes or anxiety-related awakenings
• Pre-sleep cognitive arousal (racing thoughts, worry, rumination)
• Sleep-related safety behaviors (watching the clock, excessive time in bed, alcohol/cannabis use for sleep)

When Insomnia Is Diagnosed: Screen for Anxiety

Patients presenting with insomnia should be screened for anxiety disorders using the GAD-7 (sensitivity 89%, specificity 82% for GAD at a cutoff of 10) and, if panic disorder or social anxiety is suspected, disorder-specific measures such as the Panic Disorder Severity Scale (PDSS) or Liebowitz Social Anxiety Scale (LSAS). The PROMIS Anxiety short form provides an efficient dimensional measure calibrated with item response theory.

Clinicians should pay particular attention to whether the patient's insomnia complaint conceals unrecognized anxiety. Many patients present with "I can't sleep" when the core problem is "I can't stop worrying," but they frame the issue in sleep terms because sleep disruption feels more concrete and less stigmatized than acknowledging pervasive anxiety.

Clinical Vignette: Concealed Anxiety

A 52-year-old man is referred for insomnia by his primary care physician. He reports 18 months of difficulty falling asleep and frequent awakenings. He has tried melatonin, diphenhydramine, and improved sleep hygiene with minimal benefit. On further assessment, he reports spending time in bed "planning for the next day" and describes a pattern of reviewing potential problems, checking his phone for work emails before bed, and setting multiple alarms because he fears oversleeping for important meetings. His ISI score is 19 (moderate-severe insomnia). His GAD-7 score is 14 (moderate anxiety), which surprises him — "I didn't think I was anxious, I just have a lot on my mind."

This case illustrates how anxiety can present as insomnia when the patient normalizes chronic worry as "just how I am" or frames it as productive planning. Treating this patient's insomnia without addressing the underlying generalized worry would likely produce limited benefit.

The co-occurrence of anxiety and insomnia carries significant prognostic implications that should inform treatment planning, monitoring, and patient education.

Chronicity and Relapse

Both conditions independently tend toward chronicity, and their combination amplifies this tendency. Insomnia disorder has a natural persistence rate of approximately 40–70% at 1-year follow-up without treatment (Morin et al., 2009, longitudinal natural history study). Anxiety disorders, particularly GAD, have remission rates of only 38–58% at 5-year follow-up even with treatment. When comorbid, each condition serves as a maintaining factor for the other, reducing the probability of spontaneous remission of either and increasing the likelihood of a chronic, relapsing course.

Risk for Developing Depression

The anxiety-insomnia combination is a potent risk factor for the subsequent development of major depressive disorder. Prospective data indicate that comorbid insomnia and anxiety approximately triples the risk of new-onset depression compared to anxiety alone (Ford & Kamerow, 1989; Neckelmann et al., 2007). This three-condition cascade — from anxiety to insomnia to depression — represents a well-documented clinical trajectory that clinicians should proactively attempt to interrupt.

Physical Health Consequences

Chronic sleep disruption combined with sustained sympathetic nervous system activation (the physiological signature of comorbid insomnia and anxiety) increases cardiovascular risk. Meta-analytic data indicate that insomnia is associated with a relative risk of 1.45 for cardiovascular disease and 1.55 for cardiovascular mortality (Sofi et al., 2014). Anxiety disorders independently increase cardiovascular risk. The combination likely produces additive or synergistic cardiovascular burden through chronic inflammation (elevated CRP, IL-6), endothelial dysfunction, and sustained cortisol exposure.

Treatment Response Predictions

Clinicians should set realistic expectations. Patients with comorbid anxiety and insomnia typically require longer treatment courses, more comprehensive interventions (combined CBT-I and anxiety-focused treatment, often with pharmacotherapy), and more intensive relapse prevention than patients with either condition alone. However, the prognosis is not hopeless — CBT-I response rates in comorbid populations remain robust at approximately 55–70% (defined as ≥ 8-point reduction on the ISI), and anxiety outcomes improve when both conditions are addressed. The key prognostic factor is whether treatment addresses both conditions rather than one.

The anxiety-insomnia comorbidity presents distinctive features in several populations that warrant specific clinical attention.

Older Adults

Age-related changes in sleep architecture (reduced slow-wave sleep, increased sleep fragmentation, advanced circadian phase) interact with the high prevalence of anxiety in later life. Approximately 30–50% of older adults report significant insomnia symptoms, and late-life anxiety is frequently underdiagnosed because it presents with somatic complaints and sleep disturbance rather than overt worry. Benzodiazepine and Z-drug use in this population carries elevated risks of falls, cognitive impairment, and all-cause mortality, making non-pharmacological interventions (CBT-I, behavioral activation) particularly important. The Beers Criteria explicitly recommend against benzodiazepine use in older adults.

Military and Veteran Populations

Insomnia and anxiety co-occur at very high rates in military populations, often in the context of PTSD. VA/DoD clinical practice guidelines now recommend CBT-I as a first-line treatment for insomnia in veterans, recognizing that improving sleep has downstream benefits for PTSD and anxiety symptoms. The IMAGE trial and related VA studies have shown that CBT-I delivered in group or telehealth formats produces clinically significant improvements in both insomnia and PTSD symptom severity.

Adolescents and Young Adults

Anxiety disorders typically onset in childhood and adolescence, while insomnia risk increases during adolescence due to biological circadian phase delay, academic stress, and increased screen time. This developmental window represents a critical period for the establishment of the anxiety-insomnia comorbidity cycle. Early intervention with sleep hygiene education, circadian rhythm optimization, and anxiety-focused CBT may prevent the entrenchment of the bidirectional relationship.

Despite substantial progress, several important gaps remain in the understanding and treatment of comorbid anxiety and insomnia.

Unresolved Questions

• Precision medicine approaches: Which patients with comorbid anxiety and insomnia benefit most from insomnia-first vs. anxiety-first vs. integrated treatment? No reliable predictive biomarkers or clinical algorithms currently exist to guide this decision. Computational phenotyping using actigraphy, ecological momentary assessment, and machine learning may eventually enable personalized sequencing.
• Neuroimaging-guided treatment: While resting-state fMRI and PET studies have identified neural circuits shared by anxiety and insomnia, these findings have not yet been translated into treatment selection tools. The degree to which amygdala-mPFC connectivity normalizes with CBT-I vs. anxiety-specific CBT has not been directly compared.
• The role of sleep stages: Whether specific sleep-stage disruptions (e.g., REM fragmentation vs. slow-wave sleep deficiency) differentially predict anxiety subtype development remains unclear. Preliminary evidence suggests that REM sleep disruption may be particularly relevant to emotional processing deficits in anxiety, but this requires confirmation.
• Digital therapeutics: Digital CBT-I programs (e.g., Sleepio, SHUT-i, Somryst/Pear Therapeutics) have demonstrated efficacy for insomnia, and the Freeman et al. OASIS trial showed effects on anxiety. However, whether digital CBT-I is sufficient for patients with clinically significant comorbid anxiety disorders — as opposed to subclinical anxiety — is not established. The scalability of digital interventions makes this a high-priority research question.

Emerging Findings

Orexin receptor antagonists represent the most promising pharmacological development for this comorbidity. Unlike benzodiazepines and Z-drugs, DORAs reduce wakefulness by blocking wake-promoting orexin signaling rather than broadly enhancing GABAergic inhibition. Phase 3 trials of lemborexant and suvorexant have shown sustained efficacy for insomnia at 6–12 months without evidence of tolerance. The potential anxiolytic properties of orexin receptor blockade — supported by preclinical data showing that orexin-1 receptor antagonism reduces anxiety-like behavior in rodent models — raise the exciting possibility of a single pharmacological intervention addressing both conditions simultaneously.

Glymphatic system research has revealed that sleep is critical for brain waste clearance through the glymphatic system, and that sleep disruption impairs clearance of metabolic waste products including inflammatory cytokines. This provides a novel mechanistic pathway linking chronic insomnia to neuroinflammation, which is increasingly implicated in anxiety disorders. If confirmed, anti-inflammatory adjunctive treatments might have a role in refractory comorbid presentations.

Chronotherapy and circadian interventions — including bright light therapy, melatonin-receptor agonists (ramelteon, tasimelteon), and scheduled sleep-wake timing — are being investigated as potential augmentation strategies for patients whose insomnia-anxiety comorbidity involves circadian disruption. Evening chronotype, common in anxiety disorders, may represent a modifiable risk factor amenable to circadian phase-advancing interventions.