Insomnia

01Pathophysiology

Non-organic insomnia, as classified in the PPDGJ III, is a sleep disorder that arises without an underlying medical, neurological, or substance-related cause. The core mechanism is best understood through the 3P model (Spielman's model): Predisposing, Precipitating, and Perpetuating factors.

Predisposing factors are trait-level vulnerabilities that lower the threshold for insomnia. These include a naturally elevated arousal set-point, personality traits such as perfectionism or a tendency toward rumination, and female sex. These individuals have a baseline state of cortical and autonomic hyperarousal, meaning their hypothalamic-pituitary-adrenal (HPA) axis runs slightly "hotter" than average, producing more nocturnal cortisol and higher sympathetic tone even during attempted rest.

Precipitating factors are acute stressors (job loss, bereavement, marital conflict) that trigger the initial episode of poor sleep. In most people, sleep normalizes once the stressor resolves. However, in vulnerable individuals, the sleep disturbance persists because of what happens next.

Perpetuating factors are the maladaptive behaviors and cognitions that the patient develops in response to poor sleep. The patient begins to associate the bed with wakefulness and anxiety rather than with sleep (conditioned arousal). They spend excessive time in bed hoping to "catch up," nap during the day, and develop catastrophic thinking about the consequences of sleeplessness ("If I don't sleep tonight, I will fail my exam tomorrow"). This cognitive preoccupation is directly reflected in PPDGJ III criterion (c), which requires the presence of a preoccupation with sleeplessness and excessive concern about its daytime consequences. The anxiety about not sleeping becomes self-fulfilling: the harder the patient tries to sleep, the more aroused they become, and the cycle reinforces itself.

The resulting functional impairment in social and occupational domains, as mandated by criterion (d), is a downstream consequence of chronic sleep fragmentation. The patient's daytime concentration, mood regulation, and energy are compromised, not because of total sleep deprivation, but because of the disrupted sleep architecture and the cognitive burden of constant worry.

Importantly, the PPDGJ III explicitly states that total sleep duration is not a diagnostic criterion, because normal sleep requirements vary widely between individuals. A person who sleeps 5 hours and feels rested does not have insomnia; a person who sleeps 7 hours but is consumed by distress about sleep quality may meet the criteria.

02Classification and Clinical Manifestation

The PPDGJ III classifies non-organic insomnia under sleep disorders not attributable to organic causes. Within the broader PPDGJ III framework, related sleep disorders are distinguished as follows:

Within non-organic insomnia itself, the clinical presentation can be subcategorized by symptom pattern:

03Diagnostic Workup

Non-organic insomnia is fundamentally a clinical diagnosis. The PPDGJ III criteria serve as the diagnostic standard: the clinician must confirm all four elements through a thorough history. There is no single laboratory test or imaging study that "makes" the diagnosis.

The sleep diary is the most practical adjunctive tool. The patient records bedtime, estimated sleep onset, number and duration of awakenings, final wake time, rise time, and subjective sleep quality every morning for at least two weeks. This reveals patterns such as excessive time in bed, irregular sleep schedules, and the discrepancy between perceived and actual sleep, all of which guide treatment.

Polysomnography should not be ordered reflexively. It is reserved for cases where the history raises concern for an organic sleep disorder (loud snoring with witnessed apneas suggesting obstructive sleep apnea, leg jerking reported by a bed partner suggesting periodic limb movements, or excessive daytime sleepiness disproportionate to the degree of insomnia suggesting narcolepsy). If the clinical picture is straightforward and all PPDGJ III criteria are met without red flags, PSG adds no diagnostic value and introduces unnecessary cost.

The PPDGJ III also makes an important nuance: the coexistence of another psychiatric disorder (depression, anxiety, obsessive disorder) does not invalidate the insomnia diagnosis. Both conditions should be documented and treated independently. This is a testable concept because students often assume that insomnia in the context of depression is "just a symptom" and does not warrant separate attention.

04Management and Treatment

CBT-I is the gold standard first-line treatment. It has durable efficacy that persists well beyond the treatment period, unlike pharmacotherapy which tends to lose its effect once discontinued. The key components are:

Stimulus control retrains the association between the bed and sleep. The patient is instructed to go to bed only when sleepy, use the bed only for sleep (and intimacy), leave the bedroom if unable to sleep within 15-20 minutes, and return only when sleepy again. This directly breaks the conditioned arousal cycle described in the pathophysiology.

Sleep restriction therapy temporarily limits the time spent in bed to match the patient's actual sleep time (as documented in the sleep diary). For example, if the patient reports sleeping only 5 hours despite spending 9 hours in bed, the initial prescribed time in bed is set to 5 hours. This builds up homeostatic sleep pressure, consolidates sleep, and improves sleep efficiency. The window is then gradually expanded by 15-30 minutes as efficiency improves above 85%.

Cognitive restructuring targets the catastrophic beliefs about sleeplessness. The patient learns to challenge thoughts like "I must get 8 hours or I cannot function" and replace them with more balanced appraisals.

For pharmacotherapy, the principle is "lowest effective dose for the shortest possible duration." Z-drugs (zolpidem, zopiclone, eszopiclone) are preferred over traditional benzodiazepines because they have a more selective action on the GABA-A receptor, shorter half-lives, and somewhat lower (though not negligible) abuse potential. Prescribing beyond 4 weeks should prompt reassessment and a push toward CBT-I.

In patients with comorbid depression or anxiety, trazodone is a practical choice because it addresses both the mood disorder and the insomnia without the dependence risk of benzodiazepines. However, the PPDGJ III framework requires that comorbidities be identified and treated with their own appropriate regimens; treating insomnia alone is insufficient if an underlying depressive or anxiety disorder is driving the sleep disturbance.

Contraindications and cautions:

• Benzodiazepines and Z-drugs should be avoided or used with extreme caution in the elderly (fall risk, paradoxical agitation, cognitive impairment), in patients with a history of substance use disorders, and in pregnancy.

• Antihistamines (diphenhydramine, doxylamine) are commonly used as over-the-counter sleep aids but are not recommended for chronic insomnia due to rapid tolerance, anticholinergic side effects, and next-day sedation.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on insomnia questions is by dismissing the diagnosis when a psychiatric comorbidity is present. If a vignette describes a patient with documented anxiety disorder who also meets all four PPDGJ III criteria for non-organic insomnia, many students will select "insomnia is a symptom of the anxiety disorder" and miss the fact that the PPDGJ III explicitly instructs clinicians to diagnose and treat both conditions independently. The comorbidity does not override the insomnia diagnosis.

The second trap is choosing pharmacotherapy as the first-line treatment. Vignettes that describe a patient with chronic insomnia meeting the duration and frequency criteria are testing whether you know that CBT-I, not a sleeping pill, is the initial intervention. Pharmacotherapy is a supporting role reserved for short-term use or for cases where CBT-I is unavailable or has failed.

The third trap is confusing transient insomnia with non-organic insomnia. If the vignette describes sleep difficulty lasting only a few days to 2-3 weeks after a stressor, and the 3 nights per week for 1 month threshold is not met, the correct classification is Acute Stress Reaction or Adjustment Disorder, not non-organic insomnia. Watch the timeline carefully.

Finally, students often forget that sleep duration is explicitly excluded as a diagnostic criterion in the PPDGJ III. A vignette describing a patient who sleeps 5 hours but has no distress and no functional impairment does not have insomnia, regardless of how short that sounds. The diagnosis hinges on subjective distress, cognitive preoccupation, and functional consequences, not on a number.

The core competency being tested is the ability to apply structured diagnostic criteria rather than pattern-matching on the word "insomnia," to sequence non-pharmacological before pharmacological treatment, and to recognize that psychiatric comorbidities and insomnia require parallel, independent management.