We've all been there: Your mom is telling you to get to bed, and that bed is really cozy, but then a quick Instagram check turns into three social media rabbit holes and suddenly it's 3 a.m.

The next morning, you're cranky and can't help but nod off in class. You tell yourself you're going to jump into bed early that night, but then Netflix releases an entire new season of your favorite show ... and, well, the cycle begins again.

If it's a great show or particularly interesting Instagram rabbit hole, the sluggishness the next day might feel worth it. But there's a reason parents, educators and medical professionals all preach about getting to bed on time. There's real science about what getting just a few hours of sleep does to your brain and your body, and it's super important to keep both healthy as they are still growing.

OK, Hit Me: How Bad is No Sleep?

The immediate effects of a bad night's sleep are symptoms like crankiness, finding it difficult to concentrate and an overall sense of fatigue. This won't negatively impact your health over a long period of time, though it could have consequences that last longer than just one bad day. The lack of focus could cause you to make silly mistakes on an ultra-important test, or you might snap and say things you really regret in an Instagram story that gets blasted to all your followers.

Over time, a regular lack of sleep will lead to ever further-reaching consequences. In the long term, it can lead to an increased risk for Type 2 diabetes, high blood pressure and heart disease. Those seem like pretty grown-up concerns, but heart health is extremely important as a teen, too. Some studies have found that sleep-deprived adolescents have higher cholesterol levels, higher blood pressure and wider waist sizes. Along with contributing to poor health at the moment, those are all factors that can lead to more problems later in life.

Plus, your immune system suffers without rest, and it becomes tougher for your body to fight off everything from the common cold to more debilitating illnesses like pneumonia or mono.

Sleep is also incredibly important as you are learning to drive. Everything bad about being sleepy – slower reaction times, impaired judgement, less focus and alertness – are all the same factors that make drunk driving so dangerous. The National Highway Traffic Safety Administration estimates that drowsy driving, or driver fatigue, killed at least 795 people in 2017, and was a factor in at least 91,000 police-reported crashes and 50,000 injuries. It's one thing to put your own health in danger, but tired driving can put your life, plus your friends, family and innocent strangers, in extreme danger.

Additionally, some scientists believe sleep deprivation leads to imbalances with the hormones that control hunger. People who regularly get less than seven hours of sleep per night may produce less leptin, which helps you feel full, and more ghrelin, the hormone that makes you feel hungry. This makes it easier for sleep-deprived people to put on pounds, even if they're maintaining a diet not intended to add weight. Plus, sleep deprivation leads to increased stress, which is bad for skin. If nothing else, sleep for vanity's sake.

So How Much Sleep Do I Need?

As with anything having to do with bodies, they're all different, and you should learn to listen to yours. Most human bodies function best when they get seven to nine hours per night. Babies and young children need more; their bodies and brains are growing at such a rapid pace that they need time to rest and rejuvenate. Teenagers also typically need more than seven or eight, since teen brains are also still in the growth phase.

Pay attention to your sleep schedules, and note the days where you feel alert throughout the day, as well as the days where you find it difficult to wake and really want a nap or two. Find your sweet spot, and do everything you can to get that many hours of sleep each night.

What If I'm Trying Really Hard, I Just Can't Get to Sleep At Night?

It's normal to not get your perfect amount of hours every night. Things happen, like last-minute school projects, fun sleepovers, medical emergencies or accidentally downing an espresso at 9 p.m.

But if you're consistently getting into bed and just not being able to fall asleep, it's a good idea to take a look at your other lifestyle habits and overall health and figure out how you can get the rest you need. Here are a few quick tips that can help:

• Avoid caffeine & sugar: You might be underestimating how much caffeine and sugar affect your body. Try keeping your consumption of desserts, coffee, energy drinks, caffeinated teas and sodas to the morning or early afternoon.
• Avoid screens right before bedtime: A study has shown that the blue lights from screens can trick your body into producing melatonin, the hormone you need to get your sleep. So, even if you feel sleepy and know you need to get to bed, your body could just refuse to fall into the deep sleep you need. Try to power off at least 30 minutes before bed. If you still feel like you need to wind down, read your favorite magazine or listen to a podcast or music. 
• Stay active, but not at night: We're not saying you have to run a marathon every day. But part of sleep is giving your body a rest, and if you've been sedentary at a desk or napping all day, it's tough for your body to recognize that it needs a nighttime rest. At the same time, though, most people find that vigorous exercise right before bed gets endorphins too high to fall asleep, so try to get your workout or activity in at least two hours before you want to sleep.
• Keep a routine: We know this is difficult, and it's OK not to stick to a strict schedule every single night. But figure out the little things that help you relax and get into a bedtime routine, whether that's a hot cup of tea, some restorative yoga poses, a warm shower or putting on the same sleep podcast to listen to as you doze off. Routine-setting is especially healthy and helpful if you try to get to bed and wake up around the same time every day.
• Talk to a doctor: If none of these health and lifestyle changes help you get full nights of sleep, you may have an underlying issue like sleep apnea, restless leg syndrome, depression or anxiety. Even if you're not sure if you have any of these conditions, talking with a doctor can help you determine deeper roots of any sleep issues.