A person with an 8-hour sleep need who gets 6 hours each day for 5 days builds a sleep debt of 10 hours. As sleep debt builds, brain and body functioning deteriorate. Sleep is needed to “pay down” this debt.
While sleeping in for a morning or two may help ease symptoms like fatigue or daytime sleepiness, this is often not enough to adequately recover from sleep debt. Research has shown that it can take up to four days to recover from one hour of lost sleep and up to nine days to completely eliminate sleep debt.
We measure it over your last 14 nights of sleep, and recommend you keep it below five hours to feel and perform your best. Got more than five hours of sleep debt? It might be worth catching up on sleep to get more energy, improve your brain power, and protect your health.
How Is Sleep Debt Calculated? One way to calculate your sleep debt is to track the nights you're getting less than 7 hours of sleep. Then add up how much less sleep you got every day. So if you're only getting 6 hours of sleep Monday through Friday, by the weekend you've built up a debt of 5 hours.
You need to get three to four extra hours of sleep over the course of a weekend, plus one to two extra hours of sleep every night for the following week to pay off that sleep debt. If you've slept fewer than seven hours per night for years, it may take a few weeks of sufficient sleep to repay your sleep debt.
If a person has sleep deprivation, they can recover by getting sufficient quality sleep. However, when sleep deprivation is severe or has lasted a long time, it can take multiple nights — or even up to a week — for a person to recover.
Can some people thrive on only 4 hours of sleep every single night? It's rare, but neuroscientist Dr. Ying-Hui Fu says it can happen. Fu is a neurology professor at the University of California, San Francisco.
Short naps generally don't affect nighttime sleep quality for most people. But if you experience insomnia or poor sleep quality at night, napping might worsen these problems. Long or frequent naps might interfere with nighttime sleep.
Idiopathic Hypersomnia
This sleep disorder is characterized by difficulty waking. View Source , excessive sleepiness, and the inability to feel rested after sleeping at night or napping during the day. With this disorder, you may sleep as much as 14 to 18 hours a day.
People who owe a sleep debt have higher rates of workplace injuries, and those injuries are often severe. It's clear how this could happen. Short-term sleep deprivation causes brain fog, forgetfulness and impaired driving.
If so, you're not alone. Debt has a nasty habit of making its victims suffer from stress, anxiety and even depression, all of which in turn can lead to sleep problems. If your debts are weighing heavily upon you, it's probably for a good reason.
The Dangers of Sleeping Only 3 Hours
One major side effect may be a decrease in cognitive function and proper decision-making. This could lead to accidents, irritability, depression, or memory loss. There could be multiple physical ramifications caused by sleep deprivation as well.
36 hours without sleep
The previous side effects get more intense, and your body starts experiencing hormone imbalances, slowed metabolism, fluctuations in your appetite and body temperature, higher blood pressure, and even higher inflammatory markers.
At 48 Hours: Microsleeps and Disorientation
Dr. Drerup says that at the 48-hour mark, you're dealing with “extreme sleep deprivation.” The body begins to compensate by shutting down for “microsleeps” — 3- to 15-second bursts of rest — during which your brain switches off, Drerup says.
Worsening pain or increased difficulty breathing at night also may indicate a person needs to seek emergency medical care. However, chronic insomnia, if not associated with an injury or resultant life-threatening problem typically does not belong in the emergency department.
While insomnia can be a symptom of psychiatric disorders, like anxiety and depression, it is now recognized that sleep problems can also contribute to the onset and worsening of different mental health problems, including depression, anxiety, and even suicidal ideation.