How Much Deep Sleep Do You Need?

Do you wake up feeling tired? Do you find yourself having to take naps or guzzle caffeine throughout the day? Are your friends and co-workers starting to show concern about the growing dark circles under your eyes? If you regularly sleep under six hours a night, you probably know that a lack of quality Zzz's is to blame, but what if you're a solid 7-hour-per-night kinda guy and still suffering from chronic fatigue?

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The truth is that, while there is a recommended range of hours slept each night, how much you actually need can vary quite a lot, so no two people will have the same sleep requirements. Here's what you need to know to get adequate rest and beat fatigue over the long term, without the aid of copious cups of caffeine. 

How Many Hours of Sleep Do You Need Each Night?

Scientists actually have a very good idea of how much sleep a human being needs, since we've been carefully studying sleep health for over 100 years. Unsurprisingly, your needs vary with age, with young people generally requiring more time under the covers than most. 

According to the National Heart, Lung and Blood Institute, sleep requirements look like this:

• Children under 12 years of age: 9-12 hours per night
  Teens age 13-18: 8-10 hours per night
  Adults over the age of 18: 7-9 hours per night

The other important variable is your activity level. Seven hours per night might be enough for the average office worker, but if you're training for a marathon, you best believe your body deserves more shuteye than that. 

Luckily, you can closely monitor your sleep schedule with a journal or diary. Each morning, record how many hours you slept and how rested you feel, and very quickly a pattern will emerge. From this data, you can find where you fall on the 7-9 spectrum.

Is There Such a Thing as Too Much Sleep?

There's a popular myth that you can easily oversleep, and that sleeping too much can actually be bad for your health. While there are rare instances in which this might be occurring, sleep researchers recommend you exercise caution before jumping to this conclusion.

Why? Because more often than not, oversleeping is a symptom of sickness, or of prior fatigue/exhaustion, rather than its cause. Think about it: if you went hard over the weekend, sleeping five hours or less on Friday and Saturday night, and then overslept on Sunday night, you may have slept 10 hours on the third night, but that still only averages to 6.6 hours of sleep per night, so while you did sleep a ton on one specific night, your body still isn't adequately rested. 

However, if you don't have the excuse of a fun weekend behind you, and you're regularly sleeping 8 or 9 hours a night and still feeling groggy or tired or sluggish in the mornings, it may be time to visit a sleep specialist.

Understanding Your Sleep Cycles

Sleep scientists recognize four distinct sleep cycles that your body will go through in a typical night of rest, with three of them being NREM (non-rapid eye movement) and one being REM (rapid eye movement). The NREM cycles last between 1 and 40 minutes, while the REM cycle typically lasts between 10 minutes and an hour. 

Popular focus on REM sleep tends to overemphasize its importance relative to NREM sleep, probably because the cool things like heightened brain activity and vivid dreaming occur during REM sleep. Don't get us wrong: REM sleep is extremely important, but you need quality NREM sleep to achieve the REM state. 

Another important thing to note about sleep cycles: they get longer as the night goes on. When you first fall asleep, your body will cycle through the four sleep cycles relatively quickly, but each stage will gradually take up more and more time. The typical adult sleeping for eight hours of uninterrupted sleep will get six full cycles of sleep, from Stage 1 of NREM to full REM sleep.

Sleeping disorders, old age, brain damage and severe hormone disorders can disrupt your sleep cycle regularity, with disastrous results for your overall wellbeing, but there are also some lifestyle factors that can contribute to you being a better or worse sleeper. 

Tips for Becoming a Better Sleeper

Unless you've achieved enlightenment or inner peace, you probably can't fall asleep on command, but that doesn't mean your sleep quality is entirely outside of your control. 

Here are three major lifestyle factors that can improve or hamper your sleep quality:

• Caffeine. You don't need to cut it out entirely, but make it a habit to confine your consumption to the AM hours. The Journal of Clinical Sleep Medicine recommends you have your last cup of coffee no sooner than eight hours before you get into bed, and we kinda feel like they know what they're talking about. 
• Alcohol. Despite its initial sedative effects, alcohol can actually harm your sleep quality, either by causing heart burn / acid reflux, or by hurting your body's ability to enter REM sleep. And because alcohol is also a muscle relaxant, it can even impair your body's breathing ability, causing you to wake up more frequently during the night. Sleep scientists recommend you have your last drink of alcohol four hours before bedtime. 
• Sleep schedule. You may have heated your parents for enforcing a bedtime on you, but if you want to be a healthy, responsible adult, you're going to have to learn to enforce a sleep schedule on yourself. Consistently going to bed at the same hour and waking up at the same time is a key factor in determining sleep quality.

Shift workers, time-zone-hopping travelers, party animals and gaming addicts all have a hard time keeping a sleep schedule, but if you can minimize those unusually late nights, you'll be in better shape, sleep-wise.

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