Insomnia
Differential Diagnosis
Common Diagnoses
- Anxiety from Excess Psychological Stress (Work, Relationships, Finance)
- Clinical Depression
- Chronic Alcohol Excess
- Poor Sleep Hygiene: Hyperstimulation (e.g. Caffeine, Nicotine, Drugs, Exciting Television Films) and Daytime Naps
- Pain of Chronic Physical Illness (e.g. Osteoarthritis)
Occasional Diagnoses
- Menopausal Flushes and Sweats
- Nocturia
- External Problems (e.g. Snoring Partner, Children who Disturb Parental Sleep)
- Biorhythm Disruption: Jet Lag and Shift Work
- Respiratory Problems: Asthma, Chronic Obstructive Pulmonary Disease (COPD), Left Ventricular Failure (LVF) Commonest
- Benzodiazepine Withdrawal
- Other Medical Problem, e.g. Restless Legs Syndrome or Gord
Rare Diagnoses
- Malnutrition and Low Body Weight
- Post-Traumatic Stress Disorder
- Parasomnias: Nightmares, Night Terrors and Sleepwalking
- Hyperthyroidism
- Mania
- Sleep Apnoea (Usually Presents as ‘Tired all the Time’ [TATT]; only 30% Aware of Waking)
Ready Reckoner
Key distinguishing features of the most common diagnoses
| Stress | Depression | Alcohol | Poor Sleep Hygiene | Pain | |
|---|---|---|---|---|---|
| Slow to go off | Yes | Possible | Possible | Yes | Possible |
| Early Morning Waking | Possible | Yes | No | No | Possible |
| Low Mood | Possible | Yes | Possible | No | Possible |
| Physical Illness Too | No | No | Possible | No | Yes |
| Weight Loss | Possible | Possible | No | No | Possible |
Possible Investigations
Likely:None.
Possible:FBC, LFT, TFT.
Small Print:Investigation of primary symptom leading to insomnia (see Possible investigations).
- FBC (MCV), LFT and γGT may show evidence of chronic alcohol misuse.
- TSH will differentiate non-organic anxiety state from thyrotoxicosis.
- NOTE: Pain, nocturia, respiratory problems and sleep apnoea may require investigating in their own right.
Top Tips
- Uncover any underlying physical problem such as pain or nocturia and manage as appropriate – it is pointless adopting a ‘sleep hygiene’ approach when the problem is primarily physical.
- Don’t forget the role of alcohol; this is often an underlying or contributory cause, paradoxically taken by the patient to relieve the insomnia.
- If the diagnosis seems likely to be tension or poor sleep hygiene, establish the patient’s agenda early. Patients who simply want sleeping pills are unlikely to listen to well-intentioned advice until this issue has been discussed and resolved.
- Explain to elderly patients that sleep requirements fall with increasing age and that daytime naps are to be discouraged.
Red Flags
- Shift workers are significantly at risk of developing clinical depression. Be sure to assess carefully for this pathology in the insomniac shift worker.
- Beware of young male temporary residents presenting ‘urgently’ with insomnia. They may well be drug addicts trying to obtain a prescription for benzodiazepines.
- Bone or joint pain waking an elderly patient at night is highly significant. In the patient with known arthritis, joint replacement may be indicated; in others, it may indicate serious bony pathology such as secondaries.
- Take the problem seriously even if the cause seems trivial or obvious (e.g. a patient’s snoring) – insomnia can be extremely debilitating, and by the time patients attend, they may be desperate for help.
- Anxiety and severe weight loss with sweating and tachycardia suggests hyperthyroidism. Be sure to check TSH before deciding this is non-organic.