About one in three adults regularly gets less sleep than expert guidelines recommend. As a result, millions of Americans experience “sleep debt.” A sleep debt describes the shortfall between how much sleep you need and how much sleep you actually get.
There are many circumstances that can interfere with sleep, from night shifts to crying babies to chronic pain. Regardless of the cause, just one night of too little sleep can create a sleep debt. And night after night of inadequate sleep results in chronic sleep debt, which has serious implications for health and wellbeing.
The best way to escape the adverse effects of sleep debt is to avoid it. Understanding the causes and consequences of sleep debt may help you get the healthy sleep you need.
What Is Sleep Debt?
Sleep debt is an analogy that makes it easier to understand the way sleep deprivation works.
Like financial debt, sleep debt can accumulate over time. For example, if a person needs seven hours of sleep per night but only gets five hours each night during the work week, they will accrue ten hours of sleep debt each week.
As sleep debt increases, so does its mental and physical toll, along with the urge to “pay back” the deficit by sleeping. That said, you may not need to “repay” each hour of lost sleep to recover from sleep debt.
What Causes Sleep Debt?
Sleep debt can occur due to work or school obligations, family responsibilities, lifestyle choices, physical and mental health conditions, as well as many other factors. Some situations are more common than others.
- Long hours and long commutes: For decades, Americans have been working increasingly long hours, and since 2006, the amount of time people spend traveling to work has increased by 10%. People frequently try to compensate for time lost to work and commutes by giving up sleep.
- Shift work: People whose work schedules vary, who work long shifts, or who work night shifts may not have enough time to allot for sleep. They may also have difficulty matching their sleep schedule with their circadian rhythms.
- School obligations: Students often have school start times that are out of sync with their natural sleep-wake cycles, requiring them to get up before they’ve gotten enough sleep. Moreover, some students spend time doing homework that they would otherwise spend sleeping.
- Caregiving: Caregivers are highly likely to experience sleep difficulties, whether they are tending to a newborn baby or to a family member, friend, or client with an illness or disability. For caregivers, sleep loss can be the result of frequent night awakenings, but it also can be symptomatic of the physical and mental toll of caregiving.
- Digital distractions: Television, internet, social media, and video games can all serve as distractions that keep people from getting the sleep they need.
- Sleep disorders: Conditions such as insomnia, obstructive sleep apnea, and restless leg syndrome cause sleep disruptions that contribute to sleep debt.
- Chronic pain: Pain from conditions like arthritis and fibromyalgia can make it difficult to fall asleep, stay asleep, and get high quality sleep.
- Stress and anxiety: Stressful life circumstances can lead to sleep loss, and people with anxiety disorders may experience a heightened state of alarm that interferes with their ability to sleep.
The Effects of Sleep Debt
The human body depends on sleep to carry out nearly all of its functions, from fighting disease to converting food into energy to committing new ideas to memory. As a result, both short- and long-term sleep debt have negative consequences for the body and brain.
The Short-Term Effects of Sleep Debt
As most people know from experience, even one night of poor sleep can impact how you perform and feel the next day. In the short-term, sleep debt can cause an array of acute or immediate symptoms.
- Brain fog: Brain fog is a mental state characterized by difficulty thinking, impaired concentration, and slow reaction times
- Microsleeps: Extreme sleepiness may lead to lapses in wakefulness called “microsleeps” during moments of low activity
- Mood changes: Insufficient sleep can lead to mental state similar to depression or anxiety, marked by irritability and rapidly shifting moods
The Long-Term Effects of Sleep Debt
Long-term sleep deprivation can have all of these effects and more. Over time, it can interfere with circadian rhythms and disrupt hormones. Chronic sleep debt also appears to damage the nervous system.
Research has shown that adults who regularly sleep five or fewer hours per night are at greater risk of a number of physical and mental health conditions than those who sleep seven hours or more.
- Obesity: Research has repeatedly demonstrated strong links between sleep debt and obesity. This may be due to people being less active when they are sleep deprived, as well as being more likely to make unhealthy food choices. Sleep debt may lead to metabolic and hormone changes that promote obesity.
- Diabetes: Poor sleep has been linked to developing diabetes, potentially because sleep deprivation increases obesity risk. Additionally, sleep debt may affect blood sugar control in people who already have type 2 diabetes.
- Cardiovascular problems: People with chronic sleep debt are more likely to have high blood pressure, heart disease, heart failure, and irregular or fast heart beat. They are also at higher risk of having a stroke or a heart attack.
- Depression and anxiety: While sleep loss is a symptom of many mental health conditions, it can also contribute to their development and persistence. In particular, chronic sleep debt makes people more vulnerable to depression and anxiety.
- Impaired immune function: Sleep debt can reduce the body’s ability to defend itself against viruses, bacteria, and other potential sources of disease and infection. Because of their compromised immune function, sleep deprived people are more likely to catch the common cold and get the flu.
Studies have shown that chronic sleep debt not only increases the risk of developing one of these conditions but also increases the likelihood that a person will develop more than one chronic disease at the same time.
In addition to causing health issues, sleep debt can negatively affect quality of life. Fatigue and sleepiness make it harder to participate in enjoyable activities and can lead to conflict at work or at home.
Can You Catch Up on Sleep?
Sleep used to pay back a sleep debt is sometimes called recovery sleep or rebound sleep. Recovery sleep can help alleviate some of the physical, mental, and emotional symptoms of sleep deprivation. The body tends to sleep deeply during recovery sleep, which helps you rebound from sleep debt.
How Can You Facilitate Recovery Sleep?
There are a number of strategies for getting recovery sleep, including:
- Going to bed early
- Taking short or long naps
- Sleeping for a longer duration on the weekends
- Returning to a sleep schedule that allows you to get enough sleep
While all of these approaches can benefit you if you are sleep deprived, some have downsides. For example, naps longer than 30 minutes can leave you feeling groggy. Furthermore, making up for lost sleep on the weekends can disrupt your body’s internal sleep-wake cycle, ultimately making it harder to get enough sleep.
How Much Recovery Sleep Do You Need After Accumulating Sleep Debt?
The amount of recovery sleep you might need to overcome sleep debt depends on several factors, including the duration and severity of your sleep deprivation. A single night of insufficient sleep is easier to recover from than chronic sleep debt.
People with chronic sleep debt are likely to need more than a week of sufficient sleep to recover. Research indicates that for healthy people who regularly get one hour less of sleep than they need, it can take up to nine days of getting enough sleep to overcome the sleep debt.
Additionally, some people tolerate sleep loss better than others, a trait that may be genetic. Tolerance to sleep deprivation may also reflect the fact that some people need less sleep than others. These individual differences affect both how much sleep debt a person accumulates and how much recovery sleep they need.
If you wake up feeling refreshed several mornings in a row, that’s a good indicator that you’ve rebounded from sleep debt.
Is It Possible to Fully Recover From Sleep Debt?
Recovery sleep can eliminate fatigue and reduce the level of stress hormones in your body, but research suggests that chronic sleep debt causes problems that are hard to reverse. The lingering effects of chronic sleep deprivation can affect a number of your body’s systems and functions.
- Performance on complex physical tasks: Even after a weekend of recovery sleep, the body’s ability to perform complex tasks, like driving a car in heavy traffic, remains compromised.
- Metabolism: Chronic sleep deprivation has long-term effects on metabolism, the chemical processes that turn food into energy. In particular, it can cause people to eat more than they would while rested, which causes weight gain—a problem that persists even after recovery sleep.
- Alertness and attention: Chronic sleep debt appears to cause long-term changes to the nervous system. As a result, people may have prolonged problems with alertness and paying attention, even after engaging in recovery sleep.
Since fully recovering from sleep deprivation is difficult, it is best to focus on avoiding sleep debt in the first place.
How to Avoid Sleep Debt
The key to avoiding sleep debt is ensuring that you get enough sleep—but because the optimal amount of sleep varies from person to person, you may not be sure how much you need.
Most adults require between seven and nine hours of sleep per night, though some need less or more. To figure out how much sleep you need, begin by considering whether there are internal or external factors that could affect your body’s need for sleep, such as a health condition or a physically demanding job.
Pay attention to feedback from your body. Signs that your body may not be getting the sleep it needs include dozing off in the daytime, having trouble focusing, or making mistakes at work. Also, if you have trouble functioning without multiple cups of coffee, or if you feel it is necessary to sleep in or nap on the weekends, you may not be getting enough sleep.
You might also consider these questions:
- How many hours of sleep do you need to wake up feeling refreshed and energetic?
- How much sleep does it take for you to feel alert all day, even during calm or boring activities?
- How long do you sleep when you’re able to sleep as long as you’d like?
When you feel refreshed upon waking and alert throughout the day, that’s a good indicator that you’re getting enough sleep.
Healthy Sleep Habits
You can make it easier to get the amount of sleep you need by cultivating healthy sleep habits, also known as sleep hygiene.
- Stick to a regular sleep schedule: Go to bed at the same time every night, and wake up at the same time every morning. This will help prevent disruptions in your circadian rhythms.
- Establish a bedtime routine: In the evening hours, engage in relaxing activities that help you feel calm, such as reading, taking a bath, or doing yoga.
- Avoid activities that might inhibit sleep: Screen time, vigorous exercise, heavy meals, and consuming alcohol or caffeine can interfere with your ability to fall or stay asleep. Avoid these activities in the hours before bedtime.
- Create a soothing sleep environment: Keep the bedroom dark, quiet, and relatively cool. Quiet or remove any devices, such as phones, that might interrupt your sleep. Consider using earplugs or a white noise machine. Make sure your bedding is comfortable.
- Take steps for better sleep during the day: Exposure to sunshine and physical activity early in the day can help prepare you for better nighttime sleep.
If you try these suggestions but still find yourself struggling to get the sleep you need, reach out to your doctor to discuss next steps.
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