How Caffeine Affects Sleep: What CPAP Users Need to Know

Ahhhh, caffeine! Its effects on mood and wakefulness are appreciated worldwide. And the delivery systems we use for that little stimulant are half the fun. Coffee, soda, energy drinks—they’re delicious, warming, nostalgic, and emotionally comforting. Whether you’re a daily drinker or a once-a-week indulger, the smell of a hot cup of coffee or the burn of an ice-cold Pepsi taps into something deep and familiar. Those flavor experiences bring you back again and again to the intake of caffeine.

I’m not here to debate whether caffeine is “good” or “bad” for you. But in the context of sleep, especially for people using CPAP therapy, there’s one point that absolutely matters:

caffeine affects your sleep far more than you think.

Working in a Durable Medical Equipment office and helping patients set up their ResMed CPAP machines and supplies, I hear this line constantly:

“I can drink caffeine right before bed — it doesn’t affect me at all.”

My response is always the same:

“If it doesn’t affect you… why do you need it the next day?”

Don’t lie to yourself. It affects you. That’s why you keep reaching for it.

How Caffeine Works: The Simple “Duct Tape” Explanation

To understand how caffeine disrupts sleep, imagine a heavy piece of duct tape over a keyhole.

Your body produces a chemical called adenosine as a byproduct of energy use. The more energy you burn throughout the day, the more adenosine builds up. It binds to receptors in your brain and creates something called sleep pressure—the natural push that signals your body to slow down, relax, and eventually fall asleep.

When everything is working correctly, that sleep pressure becomes your reliable bedtime cue.

But caffeine changes that.

Caffeine blocks those adenosine receptors—like duct tape over the keyhole—so adenosine cannot bind and signal that it’s time to sleep. You feel more awake, more alert, and more capable of powering through whatever you’re doing.

That’s great when you’re driving or trapped in a painfully dull meeting.

But it’s not what you want happening when you’re trying to wind down for the night.

Why Sleep Pressure Matters for CPAP Users

Good sleep isn’t just about “time spent in bed.” It’s about achieving physiologically restorative sleep—the kind of deep rest that repairs your body, supports memory, balances hormones, and keeps you functioning at your best.

That’s also what CPAP and BiPAP therapy are designed to restore.

Machines like the ResMed AirSense 11 or AirSense 10 help you breathe steadily through the night, but even the best CPAP therapy can’t fully compensate if caffeine is disrupting your sleep cycles or pushing your bedtime later without you realizing it.

Your natural sleep pressure is your friend, not your enemy. Let it do its job.

The Bottom Line

If you value your sleep, your energy, or your CPAP therapy results, be mindful of how late in the day you consume caffeine. Even if you think it “does nothing,” the science says otherwise.

Let caffeine help you when you need it—
but let your sleep pressure help you when you need that even more.