Chronic insomnia remains a frequent yet often undertreated presentation in primary care. This article outlines a circadian-informed, evidence-based framework to guide assessment and management in the Singapore clinical context.
Insomnia remains one of the most common sleep complaints encountered in primary care in Singapore.
While often perceived as a secondary symptom of stress or ageing, chronic insomnia is now recognised as an independent disorder. It is associated with — and in some longitudinal studies predicts — a higher risk of depression, anxiety, cardiovascular disease, metabolic dysfunction, and reduced quality of life.
For general practitioners (GPs), effective management requires an understanding of circadian biology, careful differentiation between acute and chronic insomnia, and judicious use of pharmacological agents.
Pathophysiology – Hyperarousal and Circadian Dysregulation
Contemporary models conceptualise insomnia as a disorder of hyperarousal, involving heightened cognitive, emotional, and physiological activation. Neuroimaging and neuroendocrine studies demonstrate elevated metabolic activity and increased sympathetic nervous system activation in patients with chronic insomnia.
Sleep regulation is governed by two interacting processes:
- Homeostatic Sleep Drive (Process S) – sleep pressure accumulates during wakefulness.
- Circadian Rhythm (Process C) – regulated by the suprachiasmatic nucleus (SCN), synchronised primarily by light exposure and melatonin secretion.
Circadian misalignment is increasingly relevant in Singapore’s urban environment, where late-night screen exposure, prolonged indoor lighting, and shift work are common. Adolescents frequently present with delayed sleep phase patterns, while elderly patients may exhibit advanced sleep phase. When circadian timing is misaligned, patients often experience persistent sleep-onset insomnia despite adequate sleep opportunity.
Accordingly, there is growing clinical interest in targeting circadian timing through behavioural and light-based interventions, rather than relying solely on hypnotic medication.
First-Line Treatment: Cognitive Behavioural Therapy for Insomnia (CBT-I)
Multiple meta-analyses and international guidelines endorse Cognitive Behavioural Therapy for Insomnia (CBT-I) as the first-line treatment for chronic insomnia.
CBT-I addresses maladaptive behaviours and cognitions that perpetuate sleep disturbance and typically includes:
- Sleep restriction therapy
- Stimulus control
- Cognitive restructuring
- Relaxation training
- Sleep scheduling and circadian alignment
A landmark meta-analysis published in JAMA Internal Medicine demonstrated that CBT-I significantly improves sleep onset latency, wake after sleep onset, and sleep efficiency, with benefits that persist beyond pharmacotherapy.
Importantly, CBT-I has shown efficacy in patients with comorbid medical and psychiatric conditions — a population commonly seen in GP settings.
Where in-person access is limited, digital CBT-I platforms have also demonstrated evidence-based benefit and may provide a scalable treatment option in primary care.
Pharmacological Management – Role and Limitations
While medications may offer short-term symptomatic relief, clinical guidelines consistently recommend cautious and time-limited use.
Benzodiazepines
Benzodiazepines can be effective for sleep initiation but are associated with:
- Tolerance and dependence
- Rebound insomnia
- Cognitive impairment
- Increased risk of falls and fractures, particularly in older adults
Long-term use is linked with poorer outcomes and is generally discouraged.
Z-drugs (Zolpidem, Zopiclone)
These agents act selectively at GABA-A receptors and may have shorter half-lives than traditional benzodiazepines.
However, clinically significant adverse effects include:
- Complex sleep behaviours
- Parasomnias
- Amnesia
- Next-day psychomotor impairment
Evidence suggests that risk profiles remain relevant, especially in older adults.
Melatonin
Melatonin is particularly useful in circadian rhythm disorders and in elderly patients with reduced endogenous secretion.
Meta-analyses demonstrate modest reductions in sleep onset latency with a favourable safety profile. Timing of administration is critical — typically 2–3 hours before the desired sleep time in delayed sleep phase presentations.
Dual Orexin Receptor Antagonists (DORAs)
Dual orexin receptor antagonists (DORAs), such as lemborexant (Dayvigo), act by inhibiting wake-promoting orexin neuropeptide pathways. This represents a mechanistically distinct alternative to GABAergic hypnotics.
Unlike benzodiazepines and Z-drugs, DORAs do not act on GABA-A receptors and are not associated with the same risks of tolerance and dependence. However, long-term real-world data remain limited.
Lemborexant is approved in Singapore, though cost and access considerations may influence prescribing decisions in primary care.
Sedating Antidepressants
Agents such as trazodone and mirtazapine are commonly prescribed off-label.
Guidelines caution against routine use solely for insomnia in the absence of comorbid depression or anxiety, due to side effects including weight gain, orthostatic hypotension, and daytime sedation.
Special Populations
Elderly Patients
Older adults demonstrate increased sensitivity to sedative-hypnotics. Benzodiazepines and Z-drugs are associated with:
- Falls and fractures
- Delirium
- Cognitive impairment
Guidelines strongly recommend CBT-I as first-line treatment in this group.
Adolescents
Insomnia in adolescents often reflects delayed circadian phase rather than primary sleep pathology. Behavioural scheduling and appropriately timed melatonin are generally preferred over hypnotic medications.
Patients with Psychiatric Comorbidity
Insomnia is bidirectionally linked with depression and anxiety. Persistent insomnia increases relapse risk in mood disorders. Treating insomnia directly has been shown to improve psychiatric outcomes and reduce recurrence.
Practical GP Approach
A structured approach in primary care may include:
- Screen for:
- Depression and anxiety
- Obstructive sleep apnoea (snoring, daytime somnolence)
- Restless legs syndrome
- Substance use
- Identify the circadian pattern.
- Initiate CBT-I principles.
- If prescribing medication:
- Use the lowest effective dose
- Limit duration
- Establish a clear discontinuation plan
- Refer if:
- Insomnia is refractory
- Bipolar spectrum disorder is suspected
- Complex parasomnias are present
Conclusion
Chronic insomnia is no longer viewed merely as a symptom, but as a disorder associated with significant morbidity. Evidence strongly supports a circadian-informed, CBT-I–first approach, with pharmacological treatment reserved for short-term or adjunctive use.
For GPs in Singapore, integrating behavioural strategies with careful prescribing can improve long-term outcomes while reducing medication-related harm.
Where insomnia persists despite primary care measures, specialist evaluation may help clarify diagnosis, address psychiatric comorbidity, and develop a tailored treatment plan.
REFERENCES:
- Buysse DJ. Insomnia. JAMA. 2013;309(7):706–716.
- Riemann D, et al. The hyperarousal model of insomnia: A review. Sleep Medicine Reviews. 2010;14(1):19–31.
- Czeisler CA. Perspective: Casting light on sleep deficiency. Nature. 2013;497:S13.
- Trauer JM, et al. Cognitive Behavioral Therapy for Chronic Insomnia: A Systematic Review and Meta-analysis. JAMA Internal Medicine. 2015;175(9):1461–1472.
- Riemann D, et al. European guideline for the diagnosis and treatment of insomnia. Journal of Sleep Research. 2017;26(6):675–700.
- Glass J, et al. Sedative hypnotics in older people with insomnia: Meta-analysis. BMJ. 2005;331:1169.
- Ferracioli-Oda E, et al. Meta-analysis: Melatonin for primary sleep disorders. PLoS Medicine. 2013;10(5):e1001410.
- Rosenberg R, et al. SUNRISE 1: Efficacy and safety of lemborexant in older adults with insomnia disorder. JAMA Network Open. 2019.
- Baglioni C, et al. Insomnia as a predictor of depression: A meta-analysis of longitudinal epidemiological studies. Journal of Affective Disorders. 2011;135(1–3):10–19.
At Private Space Medical, our psychiatrists and psychologists provide evidence-based assessment and treatment for chronic insomnia and related sleep disorders. A structured consultation can help identify circadian factors, underlying mood conditions, and appropriate therapeutic options — supporting patients toward more restorative and sustainable sleep.
Dr. Tabitha Mok
Senior Consultant Psychiatrist
Senior Consultant Psychiatrist
