What is hypnic headache?

Hypnic Headache: Diagnosis and Management

Hypnic headache is a rare primary headache disorder characterized by recurrent attacks that exclusively occur during sleep, typically awakening patients at a consistent time each night, and predominantly affecting older adults. 1, 2

Clinical Features

Key Diagnostic Characteristics

• Occurs exclusively during sleep (94.8% of cases), awakening patients from sleep 1
• Typically affects older adults (average age 58 years), though can rarely occur in children 1
• Headache episodes last 15-180 minutes on average (some up to 3 hours) 2, 3
• Occurs at a consistent time each night, often during REM sleep 4
• Pain is typically:
  • Bilateral (55.5% of cases) but can be unilateral (40%) 1, 4
  • Moderate intensity (61.5%) rather than severe 1
  • Dull or pressing quality (74.4%), though can be throbbing (38%) 1, 4
• High frequency: occurs ≥10 days/month in 94.5% of patients (average 21 days/month) 1

Associated Symptoms

• Usually lacks accompanying symptoms typical of migraine
• Autonomic features (lacrimation, rhinorrhea) occur in only 7.6% of patients 1
• Motor activity during attacks is common 3
• Nausea reported in 19% of cases 4
• Photophobia/phonophobia present in only 6.8% of cases 4

Differential Diagnosis

Hypnic headache must be differentiated from other sleep-related headache disorders:

1. Migraine: May have sleep-related attacks but typically has associated symptoms (nausea, photophobia, phonophobia) and can occur during waking hours 5

2. Cluster headache: Features severe unilateral pain with prominent autonomic symptoms 5

3. Cervicogenic headache: Pain provoked by cervical movement rather than posture 5

4. Secondary headaches: Consider when red flags are present:

   • New headache pattern after age 50
   • Headache worsened by Valsalva maneuver
   • Headache that awakens from sleep (though this is the defining feature of hypnic headache)
   • Headache with focal neurological deficits 6

Diagnostic Evaluation

1. Clinical history: Focus on timing of headache (exclusively during sleep), age of onset, duration, character, and frequency

2. Neuroimaging: Brain MRI with contrast is recommended for new-onset headache in older patients to exclude secondary causes 6

3. Polysomnography: May be useful to confirm relationship with REM sleep and exclude sleep apnea 4

4. 24-hour blood pressure monitoring: To exclude nocturnal hypertension as a cause 3

Treatment

Acute Treatment

• Generally not required as attacks are self-limited
• Caffeine: Most effective acute treatment option (cup of strong coffee) 1, 3

Preventive Treatment

First-line treatment:

• Lithium: Most extensively studied with efficacy in 77.8% of patients 1, 7
  • Typical dosage: 300-600 mg at bedtime
  • Monitor for adverse effects, especially in elderly
  • Consider tapering after 3-4 months of successful treatment 7

Second-line treatments:

• Caffeine: 1-2 cups of coffee or 200-300 mg caffeine tablet before bedtime 1, 7
• Indomethacin: 25-150 mg daily, effective but often poorly tolerated 2, 7
• Melatonin: 3-5 mg at bedtime, may be used alone or as adjunct therapy 7

Treatment Outcomes

• 56.7% of patients achieve remission with treatment 1
• 72.7% of those who achieve remission have no recurrence 1
• Some patients (4.8%) experience spontaneous remission without treatment 2

Special Considerations

1. Elderly patients: Use caution with lithium and indomethacin due to increased risk of adverse effects; start with lower doses and monitor closely 6

2. Medication interactions: Consider potential drug interactions, especially in older adults who may be on multiple medications

3. Duration of therapy: Initial treatment course of 3-4 months, followed by attempted tapering; longer duration may be needed if headaches recur 7

Common Pitfalls

1. Delayed diagnosis: Average delay of 7.6 years from symptom onset to diagnosis 1

2. Misdiagnosis: Often confused with other sleep-related headache disorders or insomnia

3. Inadequate treatment trials: Sufficient duration of preventive therapy is needed before determining efficacy

4. Poor medication tolerability: Especially with lithium and indomethacin in elderly patients; consider starting with lower doses

Hypnic headache, though rare, is a distinct clinical entity with effective treatment options. Early recognition and appropriate preventive therapy can significantly improve quality of life for affected patients.