29 posts tagged with "Sleep"

The spring clock change is a one-hour circadian phase advance delivered overnight, with no adaptation period. For people with migraine that matters because circadian disruption is one of the few triggers with consistent evidence behind it, and because the migraine brain appears unusually sensitive to changes in routine timing rather than to any particular time itself. The measured effects on health outcomes in the days after the spring change are real but modest — small increases in heart attack admissions, traffic collisions and workplace injuries — and the migraine-specific evidence is thinner than the confident headlines suggest. What is well established is the mechanism: losing an hour of sleep and shifting your light exposure by sixty minutes degrades the stability that migraine prevention depends on. The practical answer is to phase-shift gradually over the preceding week rather than absorbing the whole hour at once.

There is also a confound worth naming early, because it explains a lot of misattributed attacks: in the northern hemisphere the spring change falls in March, which is one of the most barometrically unstable months of the year.

An urban heat island is the temperature difference between a built-up area and the rural land around it, typically one to three degrees Celsius as a daily average but frequently seven degrees or more on calm clear nights. The mechanism is straightforward: cities replace vegetation with materials that absorb and store solar energy, remove the evaporative cooling that plants provide, trap heat in street canyons that radiate poorly to the sky, and add waste heat from vehicles, buildings and air conditioning. For headache and migraine the significant part is not the hot afternoon, which is only modestly warmer than the surrounding countryside, but the hot night, when the difference is at maximum and sleep is what suffers. Poor sleep is among the best-evidenced migraine triggers there is, and the urban heat island systematically attacks it.

The effect is also strikingly uneven within a single city, which turns out to matter more than the city-wide average.

A winter light headache is usually driven by two separate changes, not one. The first is light quantity — indoor winter light sits somewhere around 100 to 500 lux, while even a heavily overcast outdoor day delivers several thousand, so most people spend the dark months receiving roughly an order of magnitude less light than their circadian system evolved to expect. The second is light timing — a later sunrise moves the signal that sets your body clock, which drifts sleep and melatonin release later and leaves you running a mild, permanent jet lag. Both can lower the migraine threshold. They respond to different fixes, and neither is the same thing as seasonal depression.

The distinction matters, because a lamp only fixes one of them, and only if you use it at the right hour.

Keep indoor relative humidity between 40 and 50%. Below about 30%, the mucociliary system that clears your nose dries out: mucus thickens, cilia slow, the mucosa cracks and the nose responds by swelling. Above about 55 to 60%, dust mites and mould proliferate, and for anyone sensitised to either, that means allergic inflammation and congestion. The band between them is the only region where both problems are simultaneously minimised. It is narrow because the two failure modes approach from opposite directions.

Most people who feel congested indoors are on one side of that window or the other, and the fix is different depending on which.

Muggy weather makes you tired because humid air blocks your main cooling system, and your body compensates in ways that are metabolically expensive. When sweat cannot evaporate, your heart rate rises, blood is diverted to the skin, plasma volume falls, and core temperature drifts upward. That cardiovascular work happens whether or not you are exercising. Add disrupted sleep from warm nights and mild dehydration from fluid loss without cooling benefit, and the fatigue is not psychological — it is the predictable output of a body running a continuous background load it does not run on a dry day.

The subjective experience is distinctive: heavy limbs, poor concentration, a reluctance to move, and a sense that ordinary tasks cost more than they should. Nothing about that is imaginary.

A dehumidifier helps chronic pain when the damp is producing something else — mould, dust mites, poor sleep, or a room that never feels warm. Moisture in the air does not act directly on joints or nerves. What it does is support biological growth that drives inflammation in sensitised people, block the evaporative cooling that lets you sleep properly, and make a room feel several degrees colder than the thermostat says. Fix those and a lot of people with fibromyalgia, arthritis and chronic headache report feeling better. The dehumidifier is worth trying if your rooms measure above 60% relative humidity; below that, look elsewhere.

The framing matters because "damp weather makes my joints ache" is one of the oldest observations in medicine and one of the hardest to pin down. Indoors, at least, you have levers.

A humidifier helps migraine only if dry air is contributing to your attacks — and for a meaningful minority of people, it is. There are no good randomised trials of humidification for migraine specifically, so the honest answer is that the mechanism is plausible, the intervention is cheap and low-risk, and the way to find out is to test it on yourself properly. The people most likely to benefit are those whose attacks cluster in the heating season, who wake with headache and a dry or congested nose, and whose homes measure below 30% relative humidity.

The people least likely to benefit are those whose attacks track weather systems regardless of season, or who already live somewhere humid. A humidifier does nothing for them, and running one in an already-damp house creates new problems.

Aim for 40 to 50% relative humidity indoors, measured in the room you actually spend time in, at the temperature you actually keep it. Below 30%, mucous membranes dry out, insensible fluid loss rises and dry eye sets in. Above 60%, dust mites and mould proliferate, evaporative cooling becomes less effective and sleep quality drops. The 40 to 50% band is where the curves for biological irritants, respiratory comfort and thermal comfort all sit near their minimum simultaneously — which is why building standards, allergy guidance and sleep advice converge on roughly the same numbers.

For someone tracking headache triggers, this is one of the few environmental variables you fully control, and one of the cheapest to fix.

A stuffy room gives you a headache, and carbon dioxide is probably not the direct cause — but it is the best single number you have for diagnosing the problem. Outdoor air sits around 420 parts per million. A well-ventilated occupied room stays below about 800. A closed bedroom with two sleepers and the door shut routinely reaches 2,000 to 3,000 by morning, and a packed meeting room with no fresh air supply can pass 3,000 within an hour. At those levels CO2 itself is far below any threshold for direct physiological harm, but it tells you that a large fraction of the air you are breathing is exhaled air, along with everything else that accumulates when a room is not ventilated.

That distinction between cause and indicator is the crux of the subject, and getting it right changes what you do about it. If you treat CO2 as a poison, you look for something to remove it. If you treat it as a gauge, you look for fresh air — and fresh air also removes the volatile organic compounds, odours, humidity, airborne particles and pathogens that were building up alongside it.

The practical upside is that this is one of the few headache triggers you can measure cheaply, verify quickly and often fix for nothing.