July 10, 2026
Health Focus
Coffee, Caffeine, and the Heat: What Actually Happens on a Hot Shift
All week we talked about heat. Let's close it with the drink most of us start the day with, and clear up a myth while we're at it.
First, the myth. You have probably heard that coffee dehydrates you, so drinking it in the heat digs your hole deeper. The research says otherwise. According to the Mayo Clinic, the mild diuretic effect of caffeine is offset by the water in the drink itself, so for regular coffee drinkers, that morning cup counts toward your daily fluids and does not leave you dehydrated. Black coffee is more than 95 percent water. Your body also adapts to caffeine you consume regularly, which blunts the diuretic effect even further. So the thermos in your truck is not working against your hydration the way the old advice claimed.
That does not mean caffeine is a free ride in the heat, and here is where it matters for a drilling crew. Caffeine is a stimulant. It raises your heart rate and blood pressure by blocking adenosine and prompting a small adrenaline response. On a normal day that is the pleasant lift you drink it for. On a 110-degree day, your cardiovascular system is already working hard: your heart is pumping more to move blood to the skin for cooling, and heat strain raises your heart rate on its own. Caffeine stacks on top of that load. A stronger consideration is the sugar and the megadose. Energy drinks and heavily sweetened coffees pair high caffeine with high sugar, and the sugar slows how fast your body absorbs fluid, exactly when you need it absorbed. The stimulant can also mask early fatigue, one of the warning signs the crew should be watching for.
Caffeine also lingers. Its half-life averages about five hours, meaning a cup at 6 a.m. is still half in your system at 11 a.m., and afternoon coffee can cost you the sleep your body needs to recover for the next hot day. The federal guideline for healthy adults is up to 400 milligrams of caffeine a day, roughly four to five cups of coffee.
None of this means give up coffee. It means be smart with it in the heat: enjoy your morning cup, count it as fluid, but keep water as your main drink through the shift, go easy on the sugary energy drinks, and don't let caffeine talk you out of the breaks and the sleep your body is asking for.
Key Takeaways
The dehydration myth is just that. For regular drinkers, coffee counts toward daily fluids; it does not dehydrate you.
The real heat concern is cardiovascular: caffeine raises heart rate and blood pressure on top of the load heat already puts on your heart.
Watch the sugar and the megadoses. Energy drinks pair caffeine with sugar that slows fluid absorption, and the stimulant can mask early fatigue.
Keep water as your primary drink, for most healthy adults stay under about 400 mg of caffeine a day, and protect your sleep by cutting off caffeine in the afternoon.
Sources:
Mayo Clinic: Caffeine: Is It Dehydrating or Not?
American Medical Association: What Doctors Want Patients to Know About the Impact of Caffeine
American College of Cardiology: Chronic High Caffeine Consumption Impacts Heart Rate and Blood Pressure
Notes From the Editor
I hope that everyone has had a safe and productive week.
If you are reading this first thing in the morning, trust me, it reads best with a cup of fresh brewed coffee in your hand. Remember, it is 95% water, so enjoy, you’re being healthy.
We spent this week on heat: what it does to a crew, and how to stay ahead of it. If there's one thread running through all four days, it's that the dangerous heat problems are the predictable ones. Almost every heat illness case gives warning first, and almost every one is preventable with a plan. That's a theme you'll see us come back to. And, if there is one thing I hope you take with you this week, it is to look out for each other.
Next week we act on exactly that idea. Our Safety Focus moves to project preparedness, the work that happens before the crew ever reaches the site, and the Knowledge Share heads downhole for a four-part look at submersible pumps. Two very different topics, same underlying belief: the job goes better when the thinking happens first.
Thank you for taking the time to read the newsletter this week, and for the notes and suggestions some of you sent along. Keep them coming.
Have a great weekend, and we look forward to having you back on Monday.
Stay safe out there.
Jeremy Kuhn
Founder and CEO, WaterWellResource.com
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