Here's How to Calculate How Much Sleep You Need
Learn how to calculate how much sleep your body needs and when your ideal bedtime should be.
- Certified Sleep Science Coach, Certified Stress Management Coach
We all face one enduring question: Am I getting enough sleep? When you don't, you know the next day when you're irritable, tired and have difficulty concentrating. But if getting enough sleep was easy, we'd all do it consistently. Thankfully, you can turn around your sleep with a few intentional changes in your lifestyle.
The first step in improving your sleep habits is determining whether you are getting enough sleep for your body's needs. I will teach you how to identify how much sleep you need and when to go to bed to achieve it.
How much sleep do you really need?
Everyone is different, so there is no single answer for the ideal amount of sleep a person should get. Experts recommend that the average person get between seven to nine hours each night. Where you fall in this range will depend on your genetics, age and lifestyle. Some people need more or less sleep to feel their best.
Our sleep needs change over our lifetime. Your age is a great place to start when establishing your ideal sleep time. According to the CDC, sleep requirements by age are as follows:
Sleep needs by age
| Age range | Sleep recommendation | |
| Newborns | 0-3 months | 14-17 hours per day |
| Infant | 4-12 months | 12-16 hours per day |
| Toddler | 1-2 years | 11-14 hours per day |
| Preschooler | 3-5 years | 10-13 hours per day |
| School-age children | 6-12 years | 9-12 hours |
| Teenagers | 13-17 years | 8-10 hours |
| Younger adults | 18-25 years | 7-9 hours |
| Adults | 26-64 years | 7-9 hours |
| Older adults | 65 and older | 7-8 hours |
The best way to home in on how much sleep you need is to monitor how you feel each day. Sleep trackers are a great way to track the quality and amount of sleep you get. That data can help you spot patterns and alter your habits when necessary.
What's the best time to go to bed and wake up?
Most people wake up around the same time each day because of obligations like work or school. It's bedtime that fluctuates the most. Once you've established the average amount of time you need to sleep, you can work backward from when you need to get up to find the ideal time to go to bed.
Below is a chart showing when you should go to bed to achieve either 7.5 or 9 hours of sleep, based on what time you need to wake up. Remember that the average person needs between five to 20 minutes to fall asleep, so this shouldn't be when you get in bed, but when you fall asleep. You'll want to start your nightly routine before the time listed.
Ideal sleep time schedule
| Wake time | Goal bedtime for 7.5 hours of sleep | Goal bedtime for 9 hours of sleep |
|---|---|---|
| 4 a.m. | 8:15 p.m. | 6:45 p.m. |
| 4:30 a.m. | 8:45 p.m. | 7:15 p.m. |
| 5:00 a.m. | 9:15 p.m. | 7:45 p.m. |
| 5:30 a.m. | 9:45 p.m. | 8:15 p.m. |
| 6:00 a.m. | 10:15 p.m. | 8:45 p.m. |
| 6:30 a.m. | 10:45 p.m. | 9:15 p.m. |
| 7:00 a.m. | 11:45 p.m. | 9:45 p.m. |
| 7:30 a.m. | 11:45 p.m. | 10:15 p.m. |
| 8:00 a.m. | 12:15 p.m. | 10:45 p.m. |
| 8:30 a.m. | 12:45 p.m. | 11:15 p.m. |
| 9:00 a.m. | 1:15 p.m. | 11:45 p.m. |
The more consistent you can be with your sleep/wake times, the better. One of the main processes regulating our sleep is our circadian rhythm, which is essentially an internal clock for our natural melatonin production. Our body wants to be on a cycle it recognizes. If you stay consistent, you'll start getting tired around the same time each night.
Why is sleep important?
Despite knowing how important sleep is, many people don't get enough rest regularly. So, let's dig into why sleep is crucial for nearly every aspect of our health, from preventing diseases to lowering the risks of mental health conditions like depression.
Even though we're not moving, our brain and body perform biological processes while sleeping. Our body repairs and grows tissue while our brain clears toxins, consolidates memories and reinforces learning at night.
Beyond that, sleep is essential for cognitive function. There are structures in the brain that are active while we sleep. For example, the amygdala, the brain structure in charge of the fear response, needs sleep to respond accurately. Sleep deprivation causes the amygdala to become overactive and suppress the parts of the brain that control logical thought. Put simply, you do not interpret or respond to stimuli at your best if you aren't sleeping well.
Reasons sleep is essential for health:
- Allows for removal of toxins from the brain
- It gives the brain a chance to interpret and store new information
- Reduces risk of stroke or heart disease
- Promotes a healthy immune system
- Decreases risk of health conditions like diabetes and hypertension
- Promotes weight management
- Lower symptoms of depression and anxiety
To be considered well-rested by the time you wake up, your body would have needed to successfully go through the sleep cycles approximately four to six times. Interrupted sleep from factors like sleep apnea, nocturia or a bad mattress will leave you feeling fatigued no matter how long you sleep.
What is sleep deprivation and why is it harmful?
Sleep deprivation means you're not giving your body enough sleep. It isn't limited to feeling drowsy or worn down after a night of poor sleep. Sleep deprivation can impact your physical, emotional and cognitive health and compromise your functioning.
Short-term effects of sleep deprivation:
- Impaired memory
- Concentration troubles
- Increased irritability
- Heightened negative emotional reactions
- Elevated cortisol levels
Long-term effects of sleep deprivation:
- Risk of dementia increases
- Inhibited immune response
- Increased risk of high blood pressure, heart attack and stroke
- Higher chance of depression and other mental health conditions
- Higher risk of weight gain and obesity
6 tips to improve your sleep
If you haven't been getting good sleep, don't worry; you can turn it around with a couple of intentional habit changes. Remember that it will take some time to settle into your new routine. Try to stay as consistent as possible to see the best results.
- Get some sunlight: Start your day by getting some sunshine. Light regulates our body's circadian rhythm, so being in sunlight will suppress melatonin production and help you feel more awake. You'll reset your internal clock and set yourself up for quality sleep when the sun sets.
- Add self-care to your nighttime routine: Your nighttime routine is everything you do leading up to getting into bed. Instead of scrolling through social media, try adding relaxing activities like taking a bubble bath, reading a book or doing light yoga.
- Stop drinking alcohol or caffeine before bed: You can still enjoy both and get great sleep; it all comes down to timing. Both caffeine and alcohol take a while to metabolize, so if you drink either too close to bed, it might interrupt your sleep. It's best to stop drinking both about three hours before bed.
- Turn off screens: It's easy to fall into a cycle of scrolling through your phone or watching TV at night, but the blue light from screens will sabotage your sleep. It halts our natural melatonin process.
- Start exercising: Regular physical activity can improve sleep quality by easing stress, releasing endorphins and reducing daytime sleepiness. However, it's recommended to avoid intense workouts an hour before bed.
- Invest in a new mattress: Your mattress plays a more significant role in your sleep quality than you might realize. If your bed is old or doesn't suit your sleeping needs, you'll toss and turn throughout the night. Getting a mattress that supports and keeps you comfortable will improve your sleep quality. Alternatively, if you're not ready to buy a new bed, you can invest in a mattress topper that will change how your bed feels.