Types of Insomnia
- Sleep onset insomnia: Difficulty falling asleep (taking >30 minutes to fall asleep) — linked to anxiety, hyperthyroidism, caffeine
- Sleep maintenance insomnia: Waking frequently during the night or unable to stay asleep — linked to sleep apnoea, pain, alcohol
- Early morning awakening: Waking 2–3 hours before the planned time and unable to return to sleep — classic feature of depression, cortisol excess
Medical Causes of Insomnia
| Condition | Test | Sleep Pattern and Clues |
|---|---|---|
| Hyperthyroidism | TSH (suppressed), Free T4 | Sleep onset difficulty, palpitations, sweating, anxiety, restlessness |
| Hypothyroidism | TSH (elevated) | Unrefreshing sleep, daytime fatigue, feeling exhausted despite sleeping |
| Obstructive Sleep Apnoea (OSA) | Epworth Sleepiness Scale, overnight pulse oximetry, polysomnography (sleep study) | Snoring, gasping, daytime sleepiness; SpO2 dips on monitoring |
| Iron deficiency / Restless Legs Syndrome | Ferritin (often low <50 mcg/L in RLS), CBC | Restless legs syndrome — uncomfortable urge to move legs at night; iron is critical for dopamine synthesis |
| Cortisol excess (Cushing's) | 24-hr urine cortisol, overnight 1mg dexamethasone suppression test | Early morning awakening, central obesity, hypertension, striae |
| Depression | PHQ-9 questionnaire, TSH (to exclude thyroid), Vitamin D, B12 | Early morning awakening is the classic depressive sleep pattern |
| Anxiety disorder | GAD-7 questionnaire, TSH | Racing thoughts at bedtime, sleep onset insomnia |
| Perimenopause / Menopause | FSH (elevated), LH, oestradiol (low) | Night sweats, hot flushes, waking soaked in sweat; FSH >25-40 IU/L suggests menopause |
Blood Tests to Request for Insomnia
- TSH — Both hypo and hyperthyroidism disrupt sleep in different ways
- Ferritin — Low ferritin (<50) is associated with restless legs syndrome even without anaemia
- Fasting glucose / HbA1c — Nocturnal hypoglycaemia and nocturia in diabetes disrupt sleep
- Full blood count (CBC) — Anaemia causes fatigue and poor sleep quality
- Cortisol — If Cushing's syndrome is suspected (early morning awakening, weight gain, moon face)
- FSH and oestradiol — In perimenopausal women with night sweats and sleep disturbance
Sleep Hygiene — Evidence-Based Tips
Keep consistent sleep and wake times (even weekends). Keep bedroom cool, dark and quiet. No screens 1 hour before bed (blue light suppresses melatonin). No caffeine after 2pm. Avoid alcohol — it impairs sleep architecture. Regular exercise, but not within 3 hours of bedtime. Get out of bed if unable to sleep for >20 minutes — only use bed for sleep.
CBT-I (Cognitive Behavioural Therapy for Insomnia)
CBT-I is the most effective long-term treatment for chronic insomnia — superior to sleeping pills in long-term outcomes. It includes sleep restriction therapy, stimulus control, cognitive restructuring, and relaxation techniques. Digital CBT-I programmes are also available. Sleeping pills (Z-drugs, benzodiazepines) are only for short-term use due to dependence and rebound insomnia.
Questions to Ask Your Doctor
- Should we check TSH, ferritin and vitamin D before attributing my insomnia to stress?
- Could I have sleep apnoea — can I be referred for a sleep study?
- If I'm in perimenopause, would HRT help my sleep?
- Is there a CBT-I programme you can refer me to?
- Are sleeping tablets appropriate for short-term use in my case?
Medical Disclaimer: This information is for educational purposes only. Chronic insomnia significantly impacts health and quality of life. Please consult your doctor for proper evaluation and treatment.