We’ve all been there. We lost an hour of sleep every night last week because of a looming project due at the end of the workweek. Over the weekend we slept in, in an effort to recoup those precious Zzzs. We even wake feeling like we have a little more spring in our step after our weekend snooze-a-thon. Is that it? Have we paid back our sleep debt with no lasting consequences to our health?
Defining Sleep Debt
Sleep debt is the difference between the amount of sleep we should be getting and the amount of sleep we actually get. It's a deficit that increases every time we take a few extra minutes off our nightly slumber.
Sleep researchers use the term “sleep debt” to describe a sleep deficit. In accounting, black ink indicates a profit (i.e., surplus) and red a loss (i.e, debt or deficit). But the sleep account can never run in the black; it can only be in the red (or paid off fully each night). This means we can’t sleep more than we need and store the rest away. We can only repay the sleep debt we owe.
We can’t sleep more than we need and store the rest away. We can only repay the sleep debt we owe.
The Neuroscience of Sleep Debt
Contrary to popular belief, sleep debt isn’t always associated with a negative connotation. Sleep debt naturally begins to build from the moment we wake in the morning. As this debt builds, so does the drive to sleep, which is called “homeostatic sleep drive” or “sleep load.” Yes, sleep debt is a normal, and welcomed part of our waking day. It helps us fall asleep at night.
But if sleep debt is building steadily throughout the day, how are we able to—naps aside—stay awake till sometime in the evening?
Sleep debt begins to build from the moment we wake in the morning. As this debt builds, so does the drive to sleep, which is called “homeostatic sleep drive” or “sleep load.”
The answer is that our body clock (circadian rhythm functions) allows us to postpone repayment until nighttime. It also allows us to repay the debt quicker than it was built (i.e., we can repay ~16 hours of being awake with ~8 hours of sleep). Sleep-wake cycles are a circadian function, and a general rule of thumb is that the more robust our circadian system, the easier it will be to get a good night’s sleep..
Can You Really Catch up on Lost Sleep?
The good news is that, like all debt, with effort, sleep debt can be repaid. But don’t expect catching up on sleep to be a cure-all if sleep has been neglected for a while and is going to be neglected again come Monday morning. A recent study in Current Biology showed that subjects who were only allowed enough of a sleep opportunity to get about four hours of sleep a night during four weeknights, and partially repay some of it on the weekend with extra sleep paid a cost.
The price of sleep debt in this study included measurable differences: excess calorie intake, reduced energy expenditure, increased weight gain, and metabolic changes in how the body uses insulin. Partially repaying the debt over a few weekend nights was not enough to return these to normal.
So what’s the best approach to catch-up on missed sleep? Tacking on an extra hour or two of sleep is the best way to pay back sleep debt. For the chronically sleep-deprived, it can take months to get back metabolism fully back on track and balance the sleep debt scales.
Sleep Debt: Quality and Quantity are Essential
For restorative sleep, both the hours slept and the quality of the sleep are equally as important. Some of our most refreshing sleep occurs during deep sleep. Qualia Night’s unique patented formula integrates clinically studied ingredients to give your body what it needs to have a relaxing evening and deep rejuvenating sleep.
What makes Qualia Night different is that it enhances sleep performance, empowering your body’s ability to heal, recover, and regenerate better night after night. Qualia Night is a whole-system solution to support deep sleep, cognition, immunity, and long-term sleep performance. Learn more, here.