Is There Such a Thing as Sleep Debt?

Is there such a thing as sleep debt?

Check out this answer from Consensus:

Sleep debt is a real phenomenon with significant health implications. While there is still much to learn about its mechanisms and long-term effects, the existing evidence suggests that accumulating sleep debt can lead to various physiological and psychological issues. Addressing sleep debt at both individual and societal levels could improve overall health and well-being.

Sleep debt is a term that has gained significant attention in both scientific research and popular media. It refers to the cumulative effect of not getting enough sleep, which can lead to various physiological and psychological consequences. This article explores the concept of sleep debt, its impact on health, and the ongoing debate about its existence and significance.

What is Sleep Debt?

Sleep debt is essentially the difference between the amount of sleep an individual needs and the amount they actually get. When a person consistently sleeps less than their required amount, they accumulate sleep debt. This concept is akin to financial debt, where the “borrowed” sleep must eventually be “repaid” to restore balance.

Evidence of Sleep Debt

Several studies have investigated the effects of sleep debt on various aspects of health. For instance, one study found that chronic sleep debt negatively impacts metabolic and endocrine functions, similar to the effects seen in normal aging1. Another study highlighted that habitual short sleepers tend to have higher homeostatic sleep pressure, indicating that they may harbor substantial sleep debt2.

Health Implications

The health implications of sleep debt are far-reaching. Research has shown that sleep debt is associated with poorer cardiovascular health, particularly in older women3. Additionally, sleep debt has been linked to increased emotional instability, such as anxiety and confusion, due to diminished functional connectivity between the amygdala and the anterior cingulate cortex5. Athletes with sleep debt are also more susceptible to musculoskeletal injuries, likely due to hormonal imbalances that affect muscle recovery6.

Societal Impact

Sleep debt is not just an individual issue but a societal one. A study conducted in Philadelphia found that sleep debt varies across different demographic groups, with greater sleep debt observed in younger individuals, females, and certain ethnic minorities7. This suggests that sleep debt could be a public health concern that requires targeted interventions.

The Debate

Despite the mounting evidence, the concept of sleep debt is not without controversy. Some researchers argue that the term is poorly defined and that more empirical evidence is needed to fully understand its implications4. Others question whether the extra sleep obtained on weekends or holidays is a sign of compensating for sleep debt or merely a social choice2.

Is there such a thing as sleep debt?

Stanley Coren has answered Likely

An expert from University of British Columbia in Psychology, Sleep Research, Physiology

The scientific evidence which I know best concerning the concept of a “sleep debt” comes from looking at the cognitive effects of sleep deprivation and cumulative sleep deprivation.

In my book “Sleep Thieves” I review a number of studies where individuals were given cognitive tests as they went through a period of sleep deprivation or sleep reduction. The general pattern which emerged from these studies could be inferred from those tests which could be re-scored in the form of IQ. The general finding was that a one hour reduction in sleep length (in most studies from eight hours to seven hours) resulted in a one point loss of IQ on these tests. For each hour of sleep deprivation below seven hours, test scores diminished at a rate of approximately a loss of two points of IQ per hour.

The interesting and relevant aspect of these results were that the effects accumulated over time. Thus if an individual lost two hours of sleep per night over a five night period, then at the end of this period they would effectively be operating at a level which on the tests amounted to a 15 point loss of IQ. This certainly looks like a cognitive sleep debt. Fortunately one or two nights of prolonged sleep (9 to 10 hours) seems to reset the individual’s performance levels.

Most of these studies were conducted using medical personnel, particularly interns and residents, where the sleep deprivation was a result of being on call, or working prolonged shifts. The test used in some studies were problem-solving or computational, however some more targeted tests aimed specifically at medical personnel involved things like “To Do Lists” were given a set of symptoms the individual had to list the specific tests that would be required to determine a diagnosis. These latter tests I am less happy about because it is more difficult for me to see how these test results can be converted to IQ equivalents, however the impacts were still quite great with a roughly 20% deterioration in accuracy following several nights on call.

So my conclusion is that “sleep debt” does exist at least when we are measuring cognitive efficiency using various mental tests.

Is there such a thing as sleep debt?

Jim Horne has answered Unlikely

An expert from Loughborough University in Sleep Research

Our sleep is roughly divided into deep, light and REM (dreaming) sleep, and these states occur roughly in 90 min cycles over the night. However, periods of deep sleep occur mostly in the first two cycles, whereas light sleep and REM becomes more evident in the latter cycles.

Assuming that the most important functions of sleep occur at the beginning of sleep, whereas as sleep progresses it becomes less important in this respect, then rather than all of ‘lost sleep’ having to be recovered in its entirety, it is the deep sleep which is regained. If you lose the last few hours of a night’s sleep, much of it seems not to be needed in recovery. Thus if you only have 4h sleep one night, and are short of say the last 2-3h sleep if you are a 7 h sleeper, then roughly speaking an extra hour of sleep (allowing for any extra deep sleep) the next night (ie.8h total) should be adequate.

In sum it’s the quality of sleep that counts, here, rather than quantity. By the way, there are many claims that society today suffers from chronic sleep debt, and a cause of obesity, cardiovascular disease and other disorders. I maintain in that our sleep duration has changed little over the last hundred or so, and that these apparent adverse health effects are often overstated. Besides, our sleep is more adaptable than is generally thought . Eg – by asking people, today, ‘would you like more sleep ?’ encourages positive answers, maybe indicative of sleep debt, but fails to discriminate between actual sleep need versus a desire for just sleeping for pleasure.

We can eat to excess without hunger, merely from a ‘hearty appetite’, and drink socially for enjoyment, without thirst. Similarly, we can sleep in excess of its need, just for gratification or out of boredom, reflecting an ‘appetite for sleep’ rather than a ‘sleep hunger’ of an actual sleep need.

Is there such a thing as sleep debt?

Leonie Kirszenblat has answered Near Certain

An expert from University of Queensland in Neuroscience

Yes – when you lose sleep, you need to catch up on it. This is called ‘sleep homeostasis’ and it has been studied not only in humans but in many other animals such as mice and even fruit flies. The reason you need to catch up on sleep is that sleep performs many important functions, including consolidating memories and allowing the brain to undergo plasticity (altering the strengths of connections between brain cells). When you are sleep deprived, you generally need to sleep more the next day. If you look at the brain recording of a sleep deprived person, you can also see increased slow wave activity (one of the hallmarks of sleep), indicating that the brain is trying to make up for lost sleep functions.

Is there such a thing as sleep debt?

John Axelsson has answered Likely

An expert from Karolinska Institutet in Sleep Research, Cognitive Science, Psychology, Immunology

Short or disturbed sleep results in indivuidals being more sleepy the next day and that they sleep more and deeper (more slow wave sleep) when allowed to sleep the next time. Thus, sleep debt exist. How the brain/body keeps track of the extra need for sleep is not yet well understood.

Is there such a thing as sleep debt?

Jerry  Siegel has answered Near Certain

An expert from University of California, Los Angeles in Sleep Research

When you are sleep deprived and then allowed to sleep you sleep more. The loss of sleep is termed sleep debt. However, unlike a bank transaction the debt is never exactly repaid. The ‘rebound of sleep is always less than the sleep lost for reasons that are poorly understood.