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“Sleep deprivation can affect the body in many different ways, but people tend to feel better than they are actually doing,” says Steven Holfinger, a sleep medicine specialist at Ohio State University’s Wexner Medical Center.
While any sleep loss can affect your body and impair your functioning, long-term deprivation is most concerning. Chronic sleep deprivation can lead to what experts call sleep debt: hours of sleep you’ve lost and haven’t made up over time. In general, the more debt you accumulate, the worse your body fares and the higher your risk of long-term health complications, Holfinger says.
The good news: Catching up on lost sleep can reduce your risk of health problems. The first step, though, is recognizing that you are sleep deprived.
Here are some signs to look out for — plus expert guidance to get back on track.
Minor sleep deprivation
Also called acute sleep deprivation, minor sleep deprivation means you’re getting too little sleep — temporarily.
Maybe you had one night of basically no sleep or one or two consecutive nights of less sleep than you need. This can even happen to people who are in bed for eight hours every night: If you wake up several times, you might not be getting quality sleep — and that can also lead to symptoms of minor sleep deprivation, says Rebecca Robbins, an instructor at Harvard Medical School and an associate scientist in the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital.
One telltale sign of minor sleep deprivation is daytime fogginess: a general feeling of being out of it. “Your eyes might be open, but your vigilance is decreased because your brain is in sleep mode,” says Aruna Rao, assistant professor of neurology at Johns Hopkins University School of Medicine. Most of us think it’s normal to hit an afternoon slump, but Robbins says feeling out of it in the afternoon is actually a red flag for minor sleep deprivation.
Physically, you might also be hungrier than usual, Rao says, especially for carbs and sugar. That’s because your body is trying to compensate for lost energy.
Your attention and short-term memory also take a hit with acute sleep deprivation, says Kin Yuen, a sleep medicine physician and assistant professor at the University of California at San Francisco’s Sleep Disorders Center. You might notice that it’s harder to focus at work, for example. Some mundane tasks you can do on autopilot may not be affected, she says. “But things that require sustained attention tend to deteriorate.”
With short-term sleep deprivation, it’s also harder to keep your emotions in check, leaving you feeling more irritable or reactive. And if you have anxiety or depression, your symptoms could worsen. That emotional stress can make it hard to sleep at night, which Robbins says can perpetuate a cycle of sleep deprivation.
Major sleep deprivation
Major (or chronic) sleep deprivation happens when you’re consistently not getting enough quality sleep. Maybe you’re caring for a new baby and you’ve only been logging two or three hours a night for a few weeks, or you’ve been struggling with long-term insomnia.
Either way, you haven’t been able to make up for the lost hours — and your body is taking a hit.
In general, more sleep debt leads to more extreme symptoms of deprivation — and a heightened risk of long-term health problems. Chronic sleep loss is a form of stress, which can trigger inflammation throughout your body. Rao says this can increase your risk of myriad health conditions, from heart disease to mental illness.
Chronic sleep loss can increase the risk of developing mental illnesses such as anxiety and depression, Robbins says, or worsen existing conditions. It can also impair memory much more noticeably than minor sleep deprivation. Even routine tasks may become harder to complete the longer you go without sleep, Yuen says. It also may become harder to learn new things, because your brain formulates and consolidates memories when you sleep.
Studies have also linked chronic sleep deprivation in midlife with higher incidences of dementia and Alzheimer’s disease, potentially because it’s during sleep that the brain rids itself of neurotoxins known to affect memory.
Lack of sleep also disrupts the hormones that tell your body when you’re hungry and full as well as other hormones that regulate your metabolism. Plus, “if you’re awake when you’re supposed to be sleeping, your body conserves more glucose,” Rao says. All these factors — combined with lower daytime energy levels — can increase the risk of insulin resistance, diabetes and, over time, cardiovascular disease and obesity.
Getting back on track
You can recover from sleep deprivation as long as you have an opportunity to get caught up.
First, determine how much sleep you really need. Holfinger says most adults need about eight hours, give or take an hour or so. (Younger or older people or chronically sleep-deprived people may need more.) Think about how many hours of sleep you’d need to feel rested if you didn’t have to get up in the morning and prioritize that as a routine.
Then, try to keep a consistent bed and wake time, which can keep your circadian rhythm in check (and help you fall and stay asleep at night). Before bed, Robbins recommends implementing an unwinding routine to help signal to your body it’s time to sleep.
Avoid drinking too much alcohol before bed, stop drinking caffeine in the afternoon, and stop using electronic devices a few hours before bedtime. Research has also found that exercise during the day may help with sleep at night.
If you’re chronically sleep-deprived, be patient — it took time to accumulate your sleep debt, and it’ll take time to catch up, Holfinger says.
For example, if you miss one full night of sleep, you’ll need to sleep a few extra hours for a week to make up for it. Daytime naps can help you make up for lost time, but Rao suggests limiting them to 20 minutes and before 1 p.m. so you don’t disrupt nighttime sleep.
The important thing is to notice you are sleep deprived in the first place so that you can take action to fix it. The results will be worth the effort. “Everything will function better and more efficiently if you prioritize your sleep,” Rao says.
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