Fear of Hypoglycemia: The T1D Sleep Problem That Doesn't Show Up in Your CGM Data
Your CGM says 115. Flat arrow. No active insulin. You've checked it twice. The number is completely fine. And you're still awake at 2:48am. This is not you being dramatic. This has a name: Fear of Hypoglycemia (FOH). It's a documented...
The episode, word for word
I want to tell you about the most expensive thing T1D has been doing to your sleep.
Not the alarms. Not the lows. Not the 3am math.
The stages.
Sleep isn't one thing. It's a sequence of stages, and those stages do different things, and T1D interrupts them at specific points in ways that are documented in the research and that I think you're going to find either fascinating or extremely annoying.
Possibly both.
My name is Neil Greathouse, and this is Your Best T1D Year.
All right. Sleep stages. Field guide. Let's do this.
Your sleep runs in roughly ninety-minute cycles through the night. Each cycle goes through a series of stages: light sleep, deep sleep, and REM. Light sleep is where you start. Deep sleep is where your body does its most important work. REM is where your brain does its most important work, including dreaming and memory consolidation.
OK. Quick note on REM. REM stands for Rapid Eye Movement. Named for the biological feature where your eyes move quickly during this stage. The band R.E.M.? Named after the sleep stage. Which means every single R.E.M. song, Losing My Religion, Everybody Hurts, It's the End of the World As We Know It, is technically about brain activity at 3am. I find this deeply comforting for reasons I cannot explain.
OK. Deep sleep. Also called slow-wave sleep, or NREM Stage 3. Sounds like a government clearance level. NREM Stage 3. You are not authorized for NREM Stage 3. Exactly.
This is the stage where your body releases growth hormone. Where cellular repair happens. Where your immune system does its restocking. Where your brain clears waste products through a system called the glymphatic system, which sounds made up and is absolutely real. This stage is the whole point. This is the sleep equivalent of the thing you actually came for.
T1D adults, as I mentioned last week, spend measurably less time here than non-T1D adults.
Here's why. Every time your sleep gets disrupted, an alarm, a low, a partial arousal from a CGM vibration, a moment of hypervigilance from Fear of Hypoglycemia, an elevated cortisol level from poor sleep or stress, your brain comes back up out of whatever stage it was in. Back to lighter sleep. Back to the surface.
This is like a video game where you keep respawning at Level 1. Your brain was building toward deep sleep. Something happens. Back to Level 1. Start climbing again. Something happens. Back to Level 1.
Except you don't respawn with full health. Each interruption costs something. And if the interruptions happen frequently enough, you never spend enough time in deep sleep for your body to do the work it was trying to do.
The frustrating part is that you might not feel this in a dramatic way. You might not even fully wake up. The interruptions can be subtle. Sub-threshold. Your brain surfaces, your sleep tracker might not flag it, and you have no memory of it in the morning. But the stage transition happened. The deep sleep window got shorter.
This is part of why T1D people often sleep enough hours and still wake up tired. The hours are there. But the quality of the stages inside those hours is different.
OK. Here's what I want you to take from this. Nothing you're doing wrong is causing this. The stage disruption is a documented consequence of managing a disease that doesn't stop when you go to bed. You cannot will yourself into deeper sleep stages through effort. What you can do is reduce the interruptions that keep pulling you back up.
Which is what this whole second half of the challenge is about.
Does your wearable track sleep stages? A smartwatch, a ring, anything?
If yes: look at last night's data. What percentage was listed as deep sleep? The average for most adults is around fifteen to twenty percent. That's the target. Just know your number.
If no device: that's fine. Think about how you feel in the morning most days. Does it match the number of hours you got? If not, stage quality might be part of the story.
To the person who's been sleeping seven hours and waking up feeling like they slept four. Who's been blaming themselves for being tired when they "should" have gotten enough rest.
You weren't imagining it. The hours were there. The stages were interrupted. That's different from not sleeping enough.
Now you know the difference. And we're going to use that.
You're not doing a bad job. I'm proud of you. Nobody remembers easy.
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.