How Much Sleep Do I Really Need?

“Oh man, I think I only got four hours last night.” This may be a phrase you’ve uttered after a night of tossing and turning. But getting fewer than seven hours of sleep isn’t something you should wear as a badge of honor or brush off.

We get it. It can be challenging to get just the right amount of sleep. According to the National Sleep Foundation, about half of all people in the U.S. feel sleepy from three to seven days a week. Even losing out on one or two hours of sleep can impact your mood and overall health.

“Two of the main factors that determine the amount of sleep you need are genetics and age,” says psychologist and sleep disorder specialist Michelle Drerup, PsyD, DBSM. Here’s how to find out if you’re hitting your target or if your bedtime needs a makeover.

Necessary sleep by age 

As we age, the amount of sleep our bodies need changes.

“By adulthood, most healthy people need seven to nine hours,” says Dr. Drerup. The younger you are, the more sleep you need.

Here’s how much kids and adults need, on average:

Of course, it can sometimes vary. “There are people who are short sleepers, but it’s pretty rare,” Dr. Drerup notes. “We’re not very good judges of how sleep loss affects us, and most people who think they do well on little sleep would probably function better with a little more.”

One common misconception is that older adults don’t need as much sleep as they did in middle age. “Older adults have different sleep patterns. They tend to sleep more lightly and may wake earlier in the morning,” she adds. “But you still need the same amount of sleep over 24 hours, so if you sleep less at night, you might need a nap during the day.”

How much sleep do you need in each stage?

When you sleep, your body rests, recovers and rebuilds itself through four stages. An average sleep cycle lasts about 90 minutes. Ideally, you need four to six cycles of sleep every 24 hours to feel fresh and rested.

Each cycle contains four stages: three stages of non-rapid eye movement (NREM) sleep and one rapid eye movement (REM) stage. The time spent in each stage varies the longer you’re asleep and you might bounce between stages each night.

Here’s what happens in each stage and the rough length of each one:

NREM Stage 1

This stage of light sleeping lasts five to 10 minutes. During this stage, you’re “dozing off,” as your body and brain activity begin to slow down. If you’re woken during this stage, you may feel as if you haven’t fallen asleep at all.

NREM Stage 2

During this stage of light sleeping, your muscles begin to relax as your body temperature drops and your heart rate and breathing slow down. Your eye movement stops and your brain waves slow. Stage 2 NREM sleep accounts for about 45%-50% of your time asleep (the most of any stage).

NREM Stage 3: Deep Sleep

During this stage, your body is repairing itself by regrowing tissue, strengthening your immune system and building bones and muscle. During earlier sleep cycles, this stage could last 20 to 40 minutes and gets increasingly shorter as your sleep cycles progress. As you get older, you spend less time in this stage and more time in lighter stages of sleep.

Stage 4: REM Sleep

The majority of our dreams occur during this stage of sleep. Your brain activity greatly increases and can even match or exceed your usual brain activity when you’re awake. Your muscles enter a state of temporary paralysis, except for your eyes (which move rapidly during this stage) and the muscles you need to breathe.

Usually, the first period of REM sleep occurs around 90 minutes into your sleep cycle and lasts about 10 minutes. Each of your later REM stages gets longer the more hours you remain asleep.

Why sleep matters

Sleep benefits your physical, mental and emotional health. When you’re sleeping, your body rests and recovers — even on a cellular level. But getting enough sleep is a big part of this.

Some major benefits of getting the right amount of sleep include:

• Boosting your immune system
• Strengthening your emotional processing
• Improving your mood and decreasing stress
• Improving memory function
• Improving cellular growth
• Repairing tissue and muscle recovery
• Increasing your productivity
• Improving your exercise performance

On the flip side, shortchanging your sleep long term can lead to an increased risk of a variety of issues, including:

• Diabetes
• Depression
• Heart problems
• High blood pressure
• Lowered immunity
• Obesity

How to know if you’re getting enough sleep

If you’re not sure if you’re sleep-deprived or not, there are a few ways to find out:

• Keep a sleep diary. “Track the time you go to bed and wake up and look for patterns,” Dr. Drerup suggests. “How do you feel when you wake up, in the afternoon and at the end of the day? Do you have a midafternoon slump or feel like you need an extra cup of coffee? If so, you may not be meeting your sleep needs.”
• Take a sleep vacation. “If you have the flexibility, pick a consistent bedtime and get up without an alarm for a week or two,” she recommends. If you’re sleep-deprived, you’ll probably sleep a lot longer the first few days. But after three or four days, the amount of sleep you get each night should be close to what your body needs naturally.
• Stick to a consistent bedtime. You might not have a lot of choice about what time the alarm clock rings in the morning. But you may be able to tweak your bedtime. Figure out how many hours you want to slumber, then add an extra 15 minutes to give yourself time to fall asleep.

The bottom line: Your sleep is important 

Getting enough sleep should absolutely be a priority for your health. It’s not a waste of time, by any means, to make sure you’re getting the recommended amount of deep slumber each night. And losing precious time in bed can lead to larger health problems.

If you feel like you’re having trouble getting enough sleep (or you’re still feeling sleepy after getting enough sleep), talk to a healthcare provider. They can help you get to the root of the issue.