Something doesn’t add up.
In 2024, the Army and Marine Corps fielded the Heat Illness Protection System (HIPS), wearables built specifically to catch heatstroke faster, monitoring vitals in real time to flag danger signs conventional observation misses. Lt. Col. Dave DeGroot has said the devices can detect heatstroke as much as 12 minutes sooner than a drill sergeant watching for it. That’s a real capability, fielded exactly where the problem lives.
And heatstroke cases climbed anyway: 407 in 2023, 471 in 2024, 518 in 2025, a third straight year of increases, running right through the year the faster-detection tech showed up. Total heat illness diagnoses actually ticked down slightly over the same period, with the Marine Corps and Air Force posting real drops in heat exhaustion. So the force is getting somewhat better at heat overall, and worse at exactly the outcome the new tech was built to catch. That’s not a coincidence to wave away. It’s a sign the tech is solving a different problem than the one that’s actually growing.
What HIPS is built to see
DHA epidemiologist Dr. Alexis Maule offered the more likely explanation: better field detection means units are now catching and correctly classifying hallmark heatstroke symptoms, core temperature at or above 104°F combined with a change in mental status, that used to go unrecorded or miscoded as something milder. That’s a real and valuable gain. It also tells you exactly what HIPS is instrumented to watch for: the two markers that show up once heatstroke is already underway.
Twelve minutes of earlier warning at that point is worth having. It’s the difference between a medic arriving in time and one arriving too late. But it’s a faster alarm on a fire that’s already burning, not a system that keeps the fire from starting. A number rising every year despite that alarm getting faster isn’t an argument against the alarm. It’s an argument that the fire is still starting just as often, somewhere the alarm can’t see.
The fire starts hours before the vitals do
Core temperature and mental status don’t move first. Hydration and sodium loss move first, accumulating over hours of work in heat before a body crosses into the zone HIPS is built to detect. In a five-week Connected Hydration field pilot with a national air force, sweat-sodium loss varied by as much as 3.8x between two people doing comparable work, in the same heat, under the same guidance. Two people can start a shift under identical conditions and be in entirely different physiological territory by the afternoon, one with hours of reserve left and one with almost none, and a system watching for core temperature and mental status has nothing to say about that gap until one of them is already in it.
That’s the layer sitting upstream of every heatstroke statistic in the Military Times numbers. Across 282 monitored wear sessions in that same pilot, 91% of sessions were logged and 71% ended the day in fluid surplus, with 59 dehydration alerts caught and routed to specific individuals before they became a vitals event at all. That’s not a faster version of the same detection. It’s detection at a point in the timeline where the person can still fix it themselves.
| HIPS-style vitals monitoring | Connected Hydration | |
|---|---|---|
| What it watches | Core temperature, mental status | Fluid and sodium balance |
| When it fires | Once heatstroke markers appear | While the deficit is still building |
| What a 12-minute or same-day head start buys | Faster medical response to an event underway | A chance to never reach the event |
Neither layer replaces the other. A unit that only has vitals monitoring is still blind for every hour before the crash. A unit that only has hydration data still needs a fast, accurate alarm for the rare case that gets past it anyway. The case count climbing through 2025 is what happens when only one of those two layers is fielded at scale.
Test the layer that’s missing
An 8-week Connected Hydration pilot, up to 25 service members, minimal cost to the unit, sensors and platform provided, is built to put that upstream layer on your own training calendar, next to whatever detection tools you’re already running, and show you what it catches before the next flag or vitals alert ever fires.
FAQ
FREQUENTLY ASKED QUESTIONS
Answer copyHIPS is a wearable system fielded by the Army and Marine Corps in 2024, built to catch heatstroke faster by monitoring vitals in real time and flagging danger signs that conventional observation misses. Lt. Col. Dave DeGroot has said the devices can detect heatstroke as much as 12 minutes sooner than a drill sergeant watching for it. . Keep it to one specific, falsifiable paragraph.
Cases have risen three years running: 407 in 2023, 471 in 2024 and 518 in 2025. Total heat illness diagnoses ticked down slightly over the same period, with the Marine Corps and Air Force posting real drops in heat exhaustion.
Part of the rise is better detection. DHA epidemiologist Dr. Alexis Maule has explained that improved field detection means units now catch and correctly classify hallmark heatstroke symptoms that previously went unrecorded or were miscoded as something milder. That is a genuine gain in data quality rather than purely a rise in events.
The hallmark markers are core temperature at or above 104°F combined with a change in mental status. Those are the two signs vitals-based monitoring is instrumented to watch for, and both appear once heatstroke is already underway.
Fluid and sodium loss accumulate over hours of work in heat before core temperature and mental status change. Two people can begin a shift under identical conditions and be in entirely different physiological territory by afternoon, one with hours of reserve and one with almost none, well before either crosses a vitals threshold.
Earlier detection shortens the response time to an event already underway. Prevention requires acting on the deficit while it is still building, hours before vitals move. In one field pilot, 59 dehydration alerts were routed to specific individuals before they became a vitals event at all.
No, and neither replaces the other. Vitals monitoring provides a fast, accurate alarm once heatstroke markers appear. Hydration and sodium monitoring works upstream, on the fluid deficit accumulating for hours beforehand. A unit with only vitals monitoring is blind for every hour before the crash.
Vitals-based systems such as HIPS have been reported to detect heatstroke as much as 12 minutes earlier than direct observation. That head start is meaningful for medical response, but it begins once the event is already in progress rather than while the underlying deficit is still developing.
References
- Military Times. Military heatstroke cases still on the rise as units push tech, awareness. 29 July 2026. militarytimes.com/news/your-military/2026/07/29/military-heatstroke-cases-still-on-the-rise-as-units-push-tech-awareness/