From the Guidelines
Laboratory tests for insomnia should be ordered selectively based on clinical suspicion rather than routinely for all patients. Initial evaluation typically includes a comprehensive sleep history and physical examination without immediate laboratory testing. When clinical findings suggest underlying medical conditions, targeted tests may include complete blood count to assess for anemia, thyroid function tests to rule out thyroid disorders, comprehensive metabolic panel to evaluate liver, kidney function and electrolyte imbalances, and ferritin levels to check for iron deficiency. Additional tests might include vitamin B12 and folate levels if nutritional deficiencies are suspected, inflammatory markers if chronic inflammation is a concern, and drug screens when substance use might be contributing to sleep disturbances. Specialized sleep studies like polysomnography are reserved for cases where sleep-disordered breathing or periodic limb movement disorder is suspected, as stated in 1. This selective approach to laboratory testing is preferred because most insomnia cases are related to psychological, behavioral, or environmental factors rather than underlying medical conditions that would be detected through blood work. According to 1, the use of laboratory tests and sleep studies should be guided by clinical judgment and suspicion of underlying conditions, rather than routine testing for all patients with insomnia.
Some key points to consider when evaluating insomnia include:
- Comprehensive sleep history and physical examination
- Targeted laboratory tests based on clinical suspicion
- Reserved use of specialized sleep studies like polysomnography
- Consideration of psychological, behavioral, and environmental factors contributing to insomnia
- Selective use of laboratory tests to rule out underlying medical conditions, as recommended in 1.
It's essential to prioritize patient-reported sleep-associated distress and global outcomes over laboratory assessment, as stated in 1. By taking a selective and patient-centered approach to laboratory testing, clinicians can provide more effective and efficient care for patients with insomnia.
From the Research
Laboratory Tests for Insomnia
The following laboratory tests are recommended for patients presenting with insomnia:
- Polysomnography: to diagnose sleep disorders such as sleep apnea, restless legs syndrome, and periodic limb movement disorder 2, 3
- Actigraphy: to assess sleep patterns and diagnose sleep disorders such as insomnia, sleep apnea, and restless legs syndrome 2, 3, 4
- Sleep diaries: to assess sleep patterns and diagnose insomnia 2, 3, 4
- Multiple sleep latency test: to diagnose narcolepsy 2
Conditions that May Contribute to Insomnia
Insomnia can be associated with various somatic and psychiatric comorbidities, including:
- Restless legs syndrome 5, 2
- Circadian rhythm disorders 5
- Sleep apnea 5, 2
- Narcolepsy 2
- Major depressive disorder 4
Diagnostic Approach
The diagnosis of insomnia is primarily a clinical diagnosis based on medical history and physical examination 3. Additional tests such as polysomnography and actigraphy should be reserved for research of associated sleep disorders and for unclear situations 3.