Sleep Calculator: How Much Sleep Do You Really Need Each Night?
Too few hours of sleep or poor sleep can pave the way for a myriad of emotional and physical issues, including diabetes, obesity, heart problems, and depression.
But how do you know if the amount of sleep you’re getting each night is sufficient? Experts say that answer depends on several factors, including your age, stage of development, genetics, and your environment.
The below recommendations from the American Academy of Sleep Medicine outline the ideal amount of sleep a person needs each night depending on their each age:
Infants 4 to 12 months: 12 to 16 hours of sleep per 24 hours (including naps)
Children 1 to 2 years: 11 to 14 hours of sleep per 24 hours (including naps)
Children 3 to 5 years: 10 to 13 hours of sleep per 24 hours (including naps)
Children 6 to 12 years: 9 to 12 hours of sleep per 24 hours
Teenagers 13 to 18 years: 8 to 10 hours of sleep per 24 hours
Adults: 7 or more hours of sleep per night
These are general guidelines, but how much sleep you need to stay healthy, alert, and active can vary from person to person. Individual sleep needs are influenced by a combination of age, genetics, and behavioral, environmental, and medical factors.
For instance, you may need more sleep if you’re sick or recovering from surgery or an injury. Some people inherit certain sleep qualities like being a “short sleeper” from their parents.
Gender can also play a role, though there’s no difference in official sleep recommendations for men and women. On the whole, women tend to need a bit more sleep than men, typically because they have more issues that can affect their sleep. These include hormonal changes that come with menstruation, pregnancy, and menopause, which can disrupt women’s sleep cycles.
Furthermore, women are 40 percent more likely to have insomnia than men, and are nearly twice as likely to grapple with anxiety and depression — conditions that are both tied to sleep troubles.
While older adults need about the same amount of sleep as younger adults, their sleep habits may change. For instance, they typically go to bed earlier and wake up earlier than in their younger years. The amount of deep sleep and the time spent asleep in bed also tends to decrease as people get older, says William Lu, MD, sleep medicine physician and the medical director of the digital sleep clinic Dreem Health based in San Francisco.
Ideally, you’re able to sleep according to your circadian rhythm, your body’s natural internal clock. “Your circadian rhythm influences when your body feels sleepy or alert, so it’s what makes us feel sleepy at night,” Dr. Lu says. “When you’re able to make sure your sleep patterns align with your body's natural circadian rhythm, you can experience a more restorative sleep.”
The guidelines from the American Academy of Sleep Medicine suggest that seven or more hours of sleep each night is sufficient for adults. But how do you know if seven hours is your sweet spot or if you need closer to nine to function optimally the next day?
There are a few ways to determine your magic number. First, try keeping a sleep diary and noting what time you go to bed, wake up, your total hours of sleep, and how you feel the next day and identify patterns you see. Or, if your schedule allows, go to sleep at the same time each night without setting an alarm to wake up. Ideally, you’d do this for two weeks so you can identify the ideal number of hours your body needs.
“If you wake up before your alarm goes off in the morning, and you’re feeling refreshed, that’s a good sign your body got the right amount of restorative sleep the night before, and you’ve found what works best for you,” Lu says. “But, if you’re waking up feeling groggy and sluggish, that might be a sign to expand your sleep opportunity.”
It can also help to wear sleep monitor tools like smartwatches and rings that can identify if you’re waking up throughout the night and experiencing sleep disturbances, Lu says.
Once you know how much sleep you need each night, work backward to determine the bedtime you should aim for. This bedtime calculator factors in that the average person falls asleep within 20 minutes once in bed, though feel free to adjust if you know you fall asleep more or less quickly.
“Sleep is important for mental function, including alertness, memory consolidation, and mood regulation,” says Phyllis C. Zee, MD, PhD, director of the sleep disorders center for circadian and sleep medicine and chief of sleep medicine in the department of neurology at Northwestern University Feinberg School of Medicine in Chicago.
It impacts the body physically, too. “Data shows that with sleep loss, there are changes in the way the body handles glucose, which could lead to a state of insulin resistance (prediabetes),” Dr. Zee says. Short-term studies that link impaired glucose metabolism to nights of short sleep, as well as larger observational studies that link shorter sleepers with higher risk of diabetes, point to this conclusion.
Sleep, along with nutrition and exercise, is a pillar of health. Getting sufficient sleep at night sets you up for success in the other two areas. After all, you’ll be more likely to reach for healthy food options and have energy to get to the gym if you’re well rested.
“There is evidence that lack of sleep alters appetite regulation, which may lead to overeating or food choices that can also contribute to obesity or being overweight.”
What’s more, getting enough sleep can support heart health, boost concentration, and help keep the immune system functioning properly.
Not getting enough sleep, on the other hand, can lead to health issues including high blood pressure, diabetes, and mental health conditions like anxiety and depression. Some studies suggest poor sleep may play a role in the development of brain-related diseases like Alzheimer’s due to the accumulation of toxins in the brain, but more research is needed.
Try these tips for better sleep hygiene to help you go to sleep at your determined bedtime:
Adhere to the same wake and sleep schedule every day, even on the weekends. “Establishing and maintaining a consistent sleep schedule is a key part of waking up feeling refreshed,” Lu says.
Keep the room you snooze in on the cool side. A temperature in the low to mid 60s F is ideal.
Avoid alcohol. “It might seem like you are able to fall asleep easily with alcohol, but later in the night, alcohol has a stimulating effect, which in turn can cause you to wake up earlier,” Lu says. “Alcohol also decreases the amount of deep, restorative sleep that you get, causing you to feel more tired and less refreshed in the morning.”
Manage mental health conditions. Depression and anxiety can cause changes to sleep, sometimes leading to sleeping too much or too little. Talk to your doctor about treatment options for these conditions, which can help improve sleep.
Power down electronics at least an hour before bed. “Things like light signal to our body that it’s time to be awake, so putting phones down and turning off nearby TVs and lights can help make falling asleep easier,” Lu says.
Stick to healthy sleep routines that promote relaxation before bed, such as a warm bath or quiet reading before you snuggle in.
Sleep in a dark room. Light stimulates the brain, so Lu suggests using blackout curtains.
Store your devices outside of the bedroom. Use an alarm clock rather than your phone to wake you up in the morning.
The Takeaway
Sleep is key to a healthy life and promotes weight maintenance, heart health, brain function, and a healthy immune system, among other benefits.
The recommendations for sleep by age can help determine how much sleep you should aim for, but pay attention to how your body feels the next day as everyone’s needs are a little different.
If you’re struggling to get to sleep at the appropriate bedtime each night, adopt bedtime techniques for better sleep, such as sticking to a routine and schedule, powering down electronics at least an hour before bed, and setting your bedroom up as a cool, dark retreat.
