Why me?
If everyone has biological rhythms, why do cluster headaches only happen to some people? What makes cluster headache patients different?
Cluster headaches don’t happen because someone “did something wrong,” and they’re not caused by lifestyle, stress, weakness, or personality.
They happen because certain people have a unique neurological wiring — a combination of built-in differences in three major systems of the brain.
⭐ 1. A hypersensitive hypothalamus (the body’s master clock)
Cluster headache patients show structural and functional differences in the posterior hypothalamus — the brain region that regulates circadian and circannual rhythms.
This part of the brain is:
- more active
- more excitable
- more responsive to changes in daylight, sleep, hormones, and seasons
For most people, these rhythms pass unnoticed. For a cluster headache patient, the same signals can trigger a pain cycle.
⭐ 2. An overreactive trigeminal pain system
The trigeminal nerve — the main pain pathway in the face — has a lower activation threshold in people with CH.
This means:
- smaller triggers lead to bigger pain
- the nerve fires harder and faster
- once activated, it sustains the pain loop more aggressively
A normal brain never reaches “cluster-level” activation. A cluster headache brain does — and easily.
⭐ 3. A hypersensitive autonomic system
Cluster attacks always involve autonomic symptoms such as:
- tearing
- nasal congestion
- facial flushing
- eyelid drooping
These come from an overactive sphenopalatine ganglion (SPG). In CH patients, the SPG responds far too strongly to hypothalamus signals.
Most people’s SPGs don’t react at all under normal rhythmic changes.
⭐ 4. A genetic predisposition
Cluster headaches run in families. Genes linked to CH influence:
- circadian rhythm regulation
- pain processing
- autonomic function
- melatonin and cortisol timing
Having these genes doesn’t guarantee CH, but it makes the entire system easier to destabilise.
⭐ 5. Hormonal rhythm abnormalities
Most cluster patients show irregularities in:
- melatonin
- cortisol
- testosterone or prolactin
- the timing of daily hormonal peaks
These rhythms are normally very stable. When they’re not, the hypothalamus is far more likely to misfire and trigger a cycle.
⭐ 6. The “triple-hit” model
Cluster headaches occur when all three systems are wired differently:
- A sensitive internal clock system
- A hyperreactive trigeminal pain pathway
- An overactive autonomic reflex loop
Each by itself is common in the general population. Having all three is rare — which is why cluster headaches are rare.
⭐ 7. Why does the first cycle usually appear in adulthood?
The hypothalamus finishes maturing in the late teens and early twenties. This is when:
- hormone rhythms stabilise
- sleep patterns shift
- stress responses change
If someone is genetically predisposed, this is often the moment the first cycle appears.
⭐ 8. Why doesn’t every genetically predisposed person get CH?
Even if the wiring is there, people still need the right combination of:
- sleep disruption
- hormonal change
- daylight or seasonal triggers
- life stress
- illness
- environmental timing
Cluster headaches happen when all of these factors line up.
Most people never hit this combination. Some do — and that’s when the first cluster cycle starts.
⭐ Summary
Cluster headaches happen only in certain people because they have a unique neurological setup:
- a hypersensitive hypothalamus
- a low-threshold trigeminal system
- an overactive autonomic system
- genetic variants affecting biological rhythms
- hormonal patterns that amplify the misfire
Everyone has biological rhythms. Only a small percentage of people have brains wired in a way that lets those rhythms trigger a cluster attack.