How Bedroom Temperature and Blue Light Affect Blood Sugar in Type 1 Diabetes
Neil wants to be upfront: this episode is going to sound like wellness content delivered by someone standing in a field in linen pants. He knows. He can't control how it sounds. What he can tell you is that there's actual research behind...
The episode, word for word
I need to tell you about a hormone.
Not a new one. You've heard of this one. Cortisol. You've probably blamed it for things. I certainly have. It's the stress hormone. The one that gets raised up like a suspect every time someone can't figure out a bad blood sugar week.
Here's the thing about cortisol that I don't think gets said clearly enough.
Cortisol isn't trying to ruin your day.
Cortisol is trying to help. It has never once in your life acted with malice. It is a useful, important hormone that is, in the modern world, very confused about what an actual emergency looks like.
My name is Neil Greathouse, and this is Your Best T1D Year.
All right. Cortisol.
Here's what cortisol was designed to do. You're a human being in an older version of the world. Something dangerous happens. Your brain fires the alarm. Cortisol floods your system. Your heart rate goes up. Your energy stores mobilize. Your blood sugar rises because your body is preparing for either a sprint or a fight. And then you either sprint or you fight and cortisol clears and your system resets and you go back to baseline.
Beautiful. Efficient. Very useful for the specific problem of being chased by something with teeth.
Here's what cortisol is dealing with now. You got an email at 9:47pm with a subject line that said "quick question" and no other context. Your brain filed it as a threat. Same mechanism. Same cortisol spike. Same blood sugar response. Same elevated heart rate.
The lion never showed up. There's no sprint. There's no fight. There's just you, lying awake at 11pm, heart mildly going, blood sugar creeping up for no reason you can explain, cortisol doing its job for a threat that does not exist.
Your body cannot tell the difference between a lion in a field and a "quick question" email at 10pm. It prepares for both the same way. Cortisol is out here doing its best. It's just been handed an impossible assignment.
OK. Here's where T1D specifically comes in.
Cortisol raises blood sugar. That's literally what it does, it signals your liver to release glucose. For people without T1D, that's covered by the feedback loop. Their pancreas compensates. For us? It just... lands. And if we don't know cortisol is running elevated because we're stressed or because we got a work email or because our cortisol is chronically elevated from poor sleep, we don't account for it. We correct for a high we don't understand. We run through the checklist. We blame the site.
It was the email. It was the cortisol. It was the loop.
Here's the full loop, and I want you to follow this.
Poor sleep raises cortisol. Elevated cortisol disrupts sleep. Elevated cortisol also raises blood sugar. Elevated blood sugar disrupts sleep. Worse sleep raises more cortisol.
This is not a loop anyone is winning inside of. This is a loop that needs to be interrupted, and the interruption point I want you to focus on is the one you have the most access to: the hour before bed.
What you do in the hour before bed determines whether cortisol is elevated or settled when you close your eyes. A work email is cortisol. A tense TV show is cortisol. A late-night argument about whose turn it is to switch the laundry is cortisol. None of these things are dangerous in the literal sense. Your body does not know that.
And for T1D people specifically, whatever is happening to your cortisol at 10pm is showing up in your blood sugar by midnight.
Not every time. T1D is never that predictable. But enough to matter.
Tonight, rate your stress level on a 1-to-10 before bed. Just internally. Don't write an essay about it. Just: what number is this?
Then check your morning blood sugar.
Do it three times this week. See if there's a pattern between your 1-to-10 and what the morning looked like.
To the person who's been running on high cortisol and not knowing it. Who's been having blood sugars that don't match the day and not knowing why. Who's been doing the work and still not seeing the results they expected.
The variable wasn't in your food log. It was in your nervous system.
You're not doing a bad job. You're doing a difficult job in a world that wasn't designed to make it easy. I'm proud of you for paying attention.
Type 1 diabetes is relentless, but managing it doesn't have to be. New episodes every Monday, Wednesday, and Friday. You're not doing a bad job, you're doing a difficult job. Nobody remembers easy.
This is the script as read on the mic, lightly tidied for reading. Education, not medical advice. Talk to your care team before you change anything about your insulin.