One might often hear complaints from airline passengers, after arriving at an airport of destination, that their first day on location was spent sleeping off the headache that greeted them at the end of their flight. Typically, your head feels like it’s grown in dimension, and your temples are pulsating with the frequency of the beacon at the airport you’ve just fled to find a hotel and a pillow upon which to rest your aching cranium.
While a slew of possible factors may be causal as triggers of such migraines, more often than not it is the altitude adaptation that is foremostly explained as the reason for one’s post-flight discomfort. Altitude does, indeed, have many physiological effects on the human condition. Here’s a review of two headache-inducing agents: hypoxia and sinusitis. We’ll briefly review some facts about the first – as deadly a condition as there can be – as it applies to flying above 10,000 feet AGL. The second won’t kill you (unless you’re an inexperienced mountaineer), but it can surely ruin the first day of an anticipated restful holiday.
The worst of the problems anyone can encounter at high altitude is the inconspicuous onset of hypoxia. With progressively less oxygen per unit volume of air to sustain your body cells and tissues, one’s body starts to weaken, and brain functions surreptitiously decay. The irony of this insidious condition lies in the fact that initially, one feels a sense of well-being or euphoria, even while one’s vision and judgement become impaired, reflexes deteriorate, and sleepiness takes hold of the body. Unconsciousness nabs you at the end of the line, and who knows what may happen from there.
It is a sobering fact elicited from general research that at FL180 without oxygen the body has as little as 20 minutes of consciousness left in its store. At FL220 without oxygen, you’ve got 8 minutes to recognize the consequences of oxygen deprivation. At FL280 without oxygen, you’ve got 3 minutes to find a supplemental supply of O2, while at FL300 without oxygen, give yourself 1 minute to start humming your favourite lullaby. Though it is true that general levels of fitness and genetic predisposition will affect the rate at which hypoxia will overcome any given individual, these represent only marginal differences that might buy you a few extra minutes, or mere seconds, to react to the developing plight of your flight.
At 10,000 feet, after a 4 hour flight, a pilot should expect a deterioration in concentration due to the thinner air to which they’ve been exposed. At 14,000 feet, laziness sets in, judgement becomes cloudy, a discolouring of one’s fingernails may begin to set-in. At 16,000 feet, a pilot can become disoriented and belligerent, euphoric as well. A complete lack of judgement can consume a pilot, a scenario easily conducive for loss of control of the aircraft. At 18,000 feet, shock can eventually set in, with loss of consciousness bringing an end to your participation in your own flight.
A headache can be a major sign of hypoxic effects. It can also be a signal of other physiological factors at work, most common of all could be an affliction suffered by some 37 million North Americans year-round: sinusitis. While you’ll never likely die from a headache resulting from sitting in an aeroplane, a sinus infection can nevertheless be a major irritant when sinus cavities become infected by bacteria caused by colds, allergies, or environmental pollutants. Go flying when gripped by these unfancied factors and you’ll risk the nuisance of a throbbing noggin during the progression of your aerial jaunt.
When afflicted with sinusitis, sinus cavities are closed due to inflammation, leaving no way for cavity-trapped pressure to equalize with the outside pressure as the aircraft is climbing to altitude. The head pain is, thus, from the pressure on the membranes above the nose and between the eyes where the sinuses are located. Opening the sinus passages, commonly with a nasal decongestant, is the quickest way to open the passages, equalize the air pressure, and relieve oneself of the pressure-induced pain of the headache.