Why Am I So Bad At Accurately Judging My Sleep?

04/30/2015 07:00 am ET | Updated Aug 07, 2015
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The Question: Can you ever really know if you've slept well?

The Answer: Let's face it: most days, it's nearly impossible to view our own sleep habits with anything other than bias. Whether you over- or underestimate your sleep quantity and quality, you're rarely on target. That's because without scientific tracking methods to confirm your sleep details, it's all a matter of perception that can be altered substantially by your given mood.

Kristen L. Knutson, Ph.D., an assistant professor in the University of Chicago's Department of Medicine and the National Sleep Foundation's Poll Fellow, explained why sleep recall is so poor. If you're in a bad mood, you're more likely to blame plausible causes, such as sleep quality, for the difficulty you're facing. On the other hand, she said, if you generally feel good, you're going to have a more positive outlook on such factors.

Knutson cited a study, recently published in the American Journal of Physiology, that explored both subjective and objective awareness of sleep deprivation in a small group of eight participants.

"The subjects were in bed four hours per night, so we know they weren't getting enough sleep, but we would ask them, 'How do you feel?' the next day," Knutson told The Huffington Post. "And of course, there were people who said they felt miserable and it was awful, and then there were other people who said they felt fine and it was no big deal."

Regardless of how the participants reported feeling, a computer-based response test told a different story: All participants performed poorly. In other words, from a cognitive perspective, those who said they felt fine suffered the same repercussions after a poor night's sleep. There was no relation indicating they were a good judge of their impairment.

"That's why when someone comes up to me and says, 'Oh, I only need four hours of sleep,' I really don't believe them," said Knutson. "Because I don't know that they know if they're impaired."

Beyond mood, our circadian rhythms can trick us into thinking we slept better than we did. According to Knutson, no matter how well or poorly you might have slept on a given night, your circadian rhythm naturally and gradually increases your alertness from the time you wake up until the early evening (minus that afternoon slump). So even if you didn't sleep well, as the day goes on you will still feel a sense of alertness.

There are consequences of our poor recall when it comes to sleep.

"Obviously drowsy driving is a scary one because it can result in fatalities, but it doesn't have to be that severe to impact your life," said Knutson. "It affects mood, relationships. It's also possible that after a while, we just get used to feeling lousy, and so that becomes our new normal. If you're sleep deprived all the time, you may forget what it feels like to feel totally rested. And then if you can't tell that you're sleep deprived, there's no negative feedback telling you to get better rest."

One solution could be sleep trackers. People who start paying attention to when they go to bed, when they wake up and how much sleep they're getting tend to be more mindful of those behaviors and consider whether any changes are necessary. And by gathering such data, users won't have to ask themselves how they slept -- they can simply look at the numbers.

"If we take someone into our laboratory and we put them in bed and hook them up to a sleep machine and send noise signals throughout the night, we watch their brain waves and know they're waking up briefly," said Knutson. "But when you ask them the next day, they don't remember a lot of those awakenings." The same holds true for personal sleep tracking. You may not remember all the restless moments, but your device will.

When it comes to picking the right tracking device for you, the options seem to be endless. But to narrow down the selection, try to go with a device that doesn't require you to keep your phone in or close to your bed, because that proximity will only harm your sleep quality despite your best efforts. Also, the more scientific you can get the better. Opting for a tracker that looks beyond your sleep and wake time, and monitors your restless moments and the number of times you fully awake during the night, will give you the most accurate reading of your sleep habits.

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