Racking Up Sleep Debt: When Lack Of Rest Builds Up

Most people realize that a lack of sleep can sap their energy and dull their thinking. But many tend to believe that if they can just keep it together until the weekend, they can clear their heads with a night or two of extra rest. A growing body of sleep research suggests that it may not be so simple. Lost sleep can add up over time, potentially creating an accumulation of “sleep debt” that may take time to clear. With each successive night that you don’t get enough rest, your sleep debt — also known as a sleep deficit — tends to grow. The larger this shortfall gets, the more your mental and physical performance can suffer. It may take as many as four days of longer-than-usual slumber to clear even an hour of sleep debt, but you can prevent sleep deficit and its potentially harmful effects by maintaining a consistent sleep schedule. For professional help getting plenty of quality sleep, schedule an online or in-person therapy session with a licensed therapist.

How much sleep should you be getting?

To properly assess your sleep debt, you may need to understand how much rest your body requires to maintain peak health and performance. People may commonly underestimate how much sleep they need.

Your sleep needs typically change throughout your lifetime, with small children requiring more sleep than older adults. There can be some variation from person to person as well. However, the following guidelines for nightly hours of sleep should be appropriate for most people:

• Infants under one year old: 12 to 17 hours of sleep
• Toddlers of one to two years: 11 to 14 hours
• Children of three to five years: 10 to 13 hours
• Children of six to 13 years: Nine to 11 hours
• Teens of 14 to 17 years: Eight to 10 hours
• Adults of 18 to 64 years: Seven to nine hours
• Older adults of 65+ years: Seven to eight hours

Studies have identified some rare individuals who can function well with less than 6.5 hours of sleep per night. This doesn’t appear to be due to a revolutionary “sleep hack,” though. Rather, the individuals in question tend to have a mutated gene for the receptors that respond to the neurotransmitters epinephrine (also referred to as adrenaline) and norepinephrine.

The mutation in question is generally far from common, so if you think you might be one of those rare individuals who need little sleep, you may want to reconsider. Sleep experts suggest it’s much more likely that you’ve just gotten used to the negative impacts of insufficient sleep. In experimental tests, people experiencing sleep deprivation tend to be unable to accurately estimate how much their fatigue affects them.

Sleep debt grows each night you don't get enough sleep

When you don’t get adequate sleep, the effects may not be limited to the next day. Recent advancements in sleep research suggest that slumber shortages tend to add up over time. This may not just apply to total sleep deprivation (in other words, staying up all night). Even getting slightly less rest than you need could contribute to a longer-term challenge.

Let’s say you stay up one hour too late for three nights consecutively. This may not seem significant, but studies suggest you may be just as sleep-deprived as if you had missed three hours of slumber in a single night. This is often what health experts mean by a sleep debt or deficit. 

Even if you’re unaware of this growing shortfall, the effects will likely be evident in cognitive tests. A 2013 study examined the effects of five days of sleep restriction followed by two “recovery” nights with 10 hours of sleep each. Though participants felt like they were back to normal after their restful nights, they still performed noticeably worse on concentration and reaction time tests.

This experiment was said to be explicitly designed to mimic the pattern of a sleep-restricted work week followed by a “catch-up” period on Friday and Saturday nights. The results offer evidence that this kind of weekend recovery sleep may not be enough to compensate for five days of reduced sleep duration.

How sleep deficit affects your mind and body

The consequences of an inadequate sleep schedule can go far beyond a bit of daytime sleepiness. 

Short-term effects

Acute sleep debt, resulting from a few days or weeks of restricted sleep, may cause:

• Reduced alertness: People who aren’t getting enough sleep typically display significantly worse performance on tests measuring alertness and focus. In particular, they often exhibit slowed reflexes and lapses in attention to their surroundings, which can be quite dangerous in some settings. Studies have found that sleep deprivation can substantially increase your risk of traffic accidents.
• Impaired memory: When you’ve built up a sleep debt, you may also have trouble recalling information, holding things in your short-term memory, and learning new facts or skills. Many aspects of memory seem to be negatively impacted by a lack of slumber.
• Worse mood: You may not be surprised to learn that failing to get enough sleep can also increase the incidence and severity of emotions like anger, anxiety, depression, and confusion.

Long-term effects of sleep deprivation

The consequences described above tend to be temporary (though, as noted earlier, they may take longer to go away than you might think). However, contemporary sleep research seems to be uncovering evidence that sleep debt can also have long-term health impacts, such as the following: 

• Increased risk of dementia: A 2022 report noted that chronic sleep deficit appears to damage and destroy brain cells while causing buildups of the biomarkers found in Alzheimer’s disease. Getting too little sleep now could mean you’re more likely to experience dementia as you age.
• Mental health conditions: Research also suggests that a long-term sleep deficit can be a risk factor for various mental health disorders, including major depression, generalized anxiety, and bipolar disorder.
• Obesity: Lack of sleep tends to make people substantially more prone to unwanted weight gain and obesity. This may be partly due to metabolic changes that make it harder to burn fat and partly because the stress associated with lost sleep can prompt unhealthy eating behaviors.
• Diabetes: In addition to a greater propensity for weight gain, sleep debt may increase your odds of developing Type 2 diabetes.
• Cardiovascular disease: You may be more prone to hypertension and coronary heart disease if you consistently sleep too little. This effect may be partly explained by the heightened risk of obesity and diabetes, but researchers have frequently identified changes in cardiovascular function following even short-term sleep restriction.

How can you get rid of sleep debt?

In the meantime, taking daytime naps may also help. They’re unlikely to cancel out your sleep deficit, but they might help you temporarily regain some of your function while you’re waiting to get back to bed. A single short “cat nap” of 15 to 20 minutes in the afternoon may be most effective.

Preventing sleep deficit

You may be better off aiming to avoid sleep debt than trying to recover from it after the fact. Maintaining a healthy sleep schedule should help you prevent poor rest's short-term and long-term effects. Here are a few evidence-based ways to get more and higher-quality sleep.

• Establishing consistent sleeping and waking times
• Practicing sleep hygiene — avoiding using screens during the last hour or two before bedtime, and, if possible, using your bed only for sleep and sex
• Avoiding caffeine in the afternoon or drinking alcohol too close to bedtime
• Adopting a regular exercise habit
• Creating a bedtime routine to signal your body that it’s time for slumber
• Using a diary to record sleep duration, sleep time, and pre-sleep activities to identify which habits work best for getting restful slumber

Therapy may help you sleep better

“Get more rest” may sound like good advice, but it’s often easier said than done. If challenges like stress, depression, and anxiety are interfering with your ability to sleep soundly, it could be helpful to get advice from a mental health professional. 

Online therapy can be particularly convenient, especially if your busy schedule is part of what’s keeping you sleep-deprived. When you’re working with a therapist over the internet, there’s normally no need to commute to sessions, which can make it much easier to fit them into your week. You may also be able to receive care faster with online therapy, as you typically don’t have to spend time on a waiting list before being matched with a licensed therapist.

In addition to being convenient, numerous studies support online therapy’s effectiveness. Several randomized trials have shown that online treatment can produce significant improvements in insomnia and related conditions like depression and anxiety. In addition to helping you shed stress and improve your mood, therapy can often help you correct dysfunctional beliefs and habits that tend to encourage the buildup of sleep debt.