Bohunk,

There's likely a good reason for the increased frequency of your headaches during a nap and at sleep at night as well as why coffee helps reduce the frequency and intensity of your attacks...

For the most part, I subscribe to the vascular theory of the cluster headache disorder and it's pathophysiology where the triggering mechanism comes as a cocktail of hormones and chemicals coursing through the vascular system triggering vasodilation and the attack...  We are entitled to our opinions...

The other theory is called neurogenic where an electrochemical signal follows a nerve synapse path to the trigeminal nerve signaling dilation on the adjacent arteries and capillaries and that signals an attack... 

In the end what signals the attack is not that important...  What counts are the factors that tend to favor or counter the triggering mechanism.

It all deals with vasoactivity (dilation and constriction) of the arteries and capillaries in and around the trigeminal nerve.  If you follow this line of reasoning, the cluster headache triggering mechanism...  what ever it is...  results in a rapid dilation of the arteries in and around the trigeminal nerve.  That in tern, causes the initial pain that is vascular in nature (some times called a shadow), and when it builds due to increased vasodilation, and that dilation physically chafes the trigeminal nerve that is also inflamed at this point...  we rocket in pain from a Kip-4 or Kip-5 to a Kip-8 and above.

Sleep, particularly deep sleep at the rapid eye movement (REM) level, results in a reduced respiration rate with a shallow tidal volume.  That results a lower PaO2 (low partial pressure of arterial O2 - less oxygen in our blood) and an elevated PaCO2 (higher than normal partial pressure of arterial CO2 - more CO2 in our blood). 

These two conditions also result in a low serum pH (high blood serum acidity) and these conditions combine to become powerful vasodilators making them favor or enhance the cluster headache triggering mechanism...  At this point, the stage is set for an attack...

If you enter deep sleep, and the triggering mechanism is present or starts with body clock regularity, sleep under the conditions above, will increase the probability of an attack...

Coffee, particularly strong coffee, contains more caffeine than Red Bull, but without the taurine...  As caffeine is a vasoconstrictor, it tends to work against the cluster headache triggering mechanism.

Oxygen therapy at flow rates that support hyperventilation do three important things to help us...  100% oxygen acts as a vasoconstrictor...  And, if we breathe 100% oxygen at flow rates that support hyperventilation (flow rates ≥ 25 liters/minute), we cast off CO2 faster than our body generates it through metabolism, this lowers the concentration of CO2 (PaCO2), and that elevates the pH (less acid in the blood stream...  also call more alkaline).

The net effect is we have three powerful vasoconstrictors working for us to abort the cluster headache attack...  hyperoxia, hypocapnia, and an elevated pH. 

As an elevated pH increases hemoglobin's affinity for oxygen, This is called the Bohr Effect, that makes hyperventilating on 100% oxygen until we reach respiratory alkalosis a process that super oxygenates the blood flow to the brain signaling a rapid and powerful vasoconstriction of the arteries and capillaries in and around the trigeminal nerve...  If we continue hyperventilating on 100% oxygen, we can abort our attacks much faster with a very high success rate... 

That's my story, and I'm sticking to it until we hear differently from competent medical experts in our disorder.

Take care,

V/R, Batch