Life’s all about balance — some days you’re uber-healthy, other days not so much. But what about sleep? Does moderation really work when it comes to snagging the recommended 7 to 9 hours of shut-eye per night?

If you half-ass it a few nights by staying up late to finish work (or, you know, to watch three episodes of “Ozark”), can you really make up for it by simply sleeping in on Saturday and Sunday? (Spoiler: Not really.)

Sleep is a deeply restorative activity in which your brain catalogs information and your body repairs itself.

Inadequate sleep has been linked to:

  • diabetes
  • heart disease
  • depression
  • weight gain
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While staying up late one night can often be easily “made up” by getting a little extra sleep the next night, shortchanging yourself regularly and trying to make up for it later is another story. In these instances, you’re building up “sleep debt” and putting your health at risk.

Sleep debt, defined

While it may not sound scientific, experts have adopted this phrase to refer to the difference between the amount of sleep you should be getting and the amount you’re actually getting. Every time you skimp, your sleep debt grows.

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It’s kinda like continuously putting charges on a high interest credit card: When you’re in chronic sleep debt, you can’t catch up on your payments.

Just take a look at these stats: One study found that it takes a whopping 4 days to fully recover from just 1 hour of lost sleep.

Another study found that people who reduced their sleep by 5 hours during the week but made up for it by sleeping in on the weekends still experienced the effects of sleep deprivation: hormonal changes, increased calorie intake, weight gain, and more.

Sleeping in on weekends also messed with people’s sleep rhythms, and they were more likely to wake up at night after sleeping in during the day.

One study found that it takes 4 days to fully recover from just 1 hour of lost sleep.

So, how do you actually “repay” your sleep debt if you can’t do it in one convenient lump sum on the weekend?

First, figure out how much sleep you (as an individual) need

It’s important to understand that not everyone needs the same amount of sleep. Some people need 9 hours, while others are good with 6 hours or less. Before you completely overhaul your routine, it’s worth doing a little experiment to determine your ideal number.

Take note of how you feel after different amounts of sleep. If you have a few days off from work, let your body sleep as much as it needs to over the course of several days — that means going to bed when you’re sleepy and waking up when you feel rested. Eventually, you’ll fall into your body’s ideal rhythm and sleep duration.

Once you have a number, you’ll know what to aim for and be able to take steps to overcome any minor or major sleep debt you build up.

Short-term changes to play catch-up: Ideal to pay back a small sleep debt

Life (and really good TV) happens, so if you don’t hit your optimal sleep quota for a night or two but you otherwise have pretty good habits, all hope is not lost.

Here are a few ways you can pay back your sleep debt pretty quickly:

  • Take a power nap of about 20 minutes in the early afternoon.
  • Sleep on the weekends, but not more than 2 hours past the time you’d usually wake up.
  • Sleep more for one or two nights.
  • Go to bed a little earlier the next night.
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Long-term changes to overhaul your routine: Ideal if you’re chronically sleep-deprived

If you experience chronic sleep debt, the above recommendations won’t help very much — they’re kinda like using a Band-Aid when you really need stitches.

Instead, you’ll want to make some long-term changes to prevent yourself from getting into debt in the first place:

  • Go to sleep 15 minutes earlier each night. Do this until you reach your desired bedtime. Trying to scale back 2 hours in a single night will only set you up for frustration.
  • Try to avoid sleeping in. And if you do sleep in, try not to sleep more than 2 hours past when you’d normally wake up, even on the weekends.
  • Get sweaty on the reg — but not too late in the day. Some vigorous exercise during the day can help you feel nice and sleepy later. But skip night workouts, which can leave you wired. Try to wrap up any exercise at least 3 hours before bed.
  • Skip the evening coffee and booze. Caffeine can mess with sleep if you drink it less than 4 to 6 hours before bed. And while alcohol makes you drowsy, it also reduces REM sleep, which is thought to be the most restorative sleep.
  • Chill the eff out with a relaxing pre-bed ritual. Your body needs time to shift into sleep mode each night. Consider a ritual away from bright lights to make the transition, like reading, taking a bath, or doing some gentle stretches to calming music.
  • Eliminate blue light. Artificial light exposure at night suppresses melatonin (the sleep hormone), so you don’t get sleepy like you should. If you can’t avoid screens altogether, at least put your phone in “night sight” mode or try using blue light-blocking glasses.
  • Avoid napping. If you struggle with sleep at night, stick to quick 20-minute catnaps, which are less likely to disrupt your slumber.
  • Soak up the morning light. Exposure to natural light in the morning helps suppress melatonin and reset your circadian rhythms so you naturally feel awake when you’re supposed to.

How sleep debt messes with your sleep cycles

Another reason staying up late and racking up sleep debt is a bad idea has to do with how your body cycles through the stages of sleep in a night.

Basically, sleep is composed of a series of 90- to 120-minute cycles, and each cycle has several stages of non-REM deep sleep followed by REM (rapid eye movement) sleep. A good night’s sleep will typically consist of 4 to 5 of these cycles.

As the night goes on, the amount of each sleep cycle devoted to REM sleep increases, while the amount of non-REM deep sleep decreases. Why is this important? Because, experts say, this shift happens regardless of when you go to bed.

Meaning: If you always get to bed late, you’re consistently missing out on early sleep cycles that are dominated by deep sleep — the type of sleep needed to repair tissue, build bone and muscle, and boost your immune system.

The perks of keeping your sleep debt to a minimum

Just to hammer the message home: Sleep is really freakin’ important. It may seem like you’re wasting valuable working or socializing hours, but rest assured, sleep is just as crucial for your health as eating well or working out.

Chronic poor sleep can have negative effects in these areas, leading to issues with several of your body’s processes. Not to mention that you’ll just feel pretty crappy all around.

In our “always on” culture, where everyone has a side hustle, sleep often gets put on the back burner: You go hard during the week and “catch up” on the weekends.

But in doing so, you’re not actually making up for the damaging health effects of your total sleep debt (the difference between how much sleep you should get and how much you actually get).

Your best bet to reverse a sleep deficit: Prioritize lifestyle changes that help you get good sleep on a regular basis. And, on the rare night you absolutely can’t get enough sleep, take strategic steps (think: catnaps or sleeping in, but not too much!) to pay off your sleep debt ASAP.