Why Your Sleep Log Might Be Lying to You (In a Good Way)
If you’ve ever done sleep math in your head like “okay, if I fall asleep by 11, I’ll get seven hours” and then woken up convinced you’ve barely slept a wink, then I want you to hear this, you might be wrong. And new research says that’s actually pretty common.
A study published in Journal of Clinical Sleep Medicine found that a large chunk of adults who describe themselves as short sleepers, aren’t once you measure their sleep objectively. And as someone who spends most of my clinical hours talking to people through exactly this kind of mismatch, I couldn’t resist breaking it down for you.
What the Study Actually Found
Research looked at data from the STITCH trial, a study built around sleep technology and cardiometabolic health, and focused on 195 adults who all reported sleeping 7 hours or less per night. Everyone in the group wore an actigraphy device (basically a research-grade sleep tracker worn on the wrist) so their sleep could also be measured objectively.
Here's where it gets interesting: on average, participants self-reported about 6.3 hours of sleep, but actigraphy measured closer to 6.8 hours. That's roughly a 29-minute underestimation, on average. And when researchers looked at the full group, only about 54% actually had objectively short sleep, meaning nearly half the people who believed they were chronically under-sleeping were, physiologically, doing better than they thought.
The self-reported and measured numbers were only loosely correlated, which tells us something important: how long you think you slept and how long you actually slept can be two pretty different stories.
Who Tends to Underestimate the Most
This part is where it starts to sound familiar to anyone who's worked with me on sleep. The people most likely to underestimate their sleep tended to have:
• Longer sleep onset latency (it takes them a while to fall asleep)
• More wake time after sleep onset (more nighttime waking)
• Higher sleep efficiency, oddly enough
• Higher scores on measures of sleep disturbance
• Higher perceived stress
In other words: the more your sleep is fragmented, effortful, or wrapped up in stress, the more likely you are to walk away from the night feeling like it was worse than it was. So, it’s not like you're "bad at sleeping." It's your nervous system doing exactly what a stressed, hyperaroused nervous system does by paying close attention to every wake-up and every restless stretch, and remembering those moments far more vividly than the stretches of solid sleep in between.
Why This Matters If You're Working on Your Sleep
If you're in CBT-I with me (or thinking about it), you already know sleep logs are a core tool and we use them to calculate your sleep window for sleep restriction therapy, track patterns, and measure progress. This study is a good reminder that perception and reality don't always match, and that's actually part of the clinical picture, not a flaw in the process.
This is sometimes called sleep state misperception or paradoxical insomnia, which is when someone's subjective experience of their sleep doesn't line up with what's actually happening physiologically. It's incredibly common, and it's one of the reasons CBT-I doesn't just take "I only got 4 hours" at face value. We look at patterns over time, we ask about how you're feeling functionally during the day, and when it's useful, we talk about incorporating objective data like a wearable alongside your diary.
It also reframes a question I hear a lot: "What if I've been panicking over nothing?" Sometimes, yes, some of the anxiety around sleep is actually about the fear of not sleeping, which itself becomes the thing keeping you awake. That's the hyperarousal loop CBT-I is designed to interrupt.
What To Do With This Information
If you read this and thought "that's me" then here's where I'd start:
Keep tracking, but hold it loosely. A sleep log is still useful, but treat your nightly estimate as a data point, not a verdict.
Notice the stress connection. If your worst sleep-perception nights line up with your most stressful days, that's worth paying attention to and it's very treatable.
Don't self-treat with more time in bed. The instinct to "catch up" by going to bed earlier or lying in longer usually backfires and can worsen insomnia. This is exactly why sleep restriction therapy is done with guidance, not alone.
Get an objective read if you're unsure. A basic wearable, or a short course of actigraphy through a sleep provider, can tell you whether your gut feeling matches reality.
The researchers behind this study put it simply: sleep extension programs should include objective assessment before enrolling people, because self-report alone is often inaccurate. I'd add that it’s true in the therapy room too. Part of my job isn't just fixing your sleep; it's helping you trust your own read on it again.
Curious what your sleep actually looks like and not just what it feels like?
If sleep has felt like a nightly guessing game, CBT-I can help you get real, measurable answers and a plan that works. I offer virtual CBT-I for clients in Illinois and Texas. Contact me today to get started on your sleep journey. Are you a therapist wanting to incorporate CBT-In into your practice to help your patients? I provide 1:1 CBT-I practice consulting and done-for-you tools to help in your practice.
