Everybody needs sleep. Our brains and bodies have evolved to be active during the day and to rest and repair at night, but because children are developing so rapidly, inadequate sleep can hold them back physically and mentally. Without enough sleep, our moods change, our ability to pay attention is impaired, it’s harder to learn and our immune systems suffer. We’re even more likely to overeat, and driving while drowsy is a significant cause of accidents.

However, too much sleep is not good either. Our bodies need to move and our brains need to be stimulated in order to stay healthy. Excessive sleep may be a sign of depression, illness or a sleep disorder that interferes with sound sleep.

The amount of sleep we need and when we need it changes throughout our lifespan. Newborns may spend more time asleep than awake, while older adults may feel fine with as little as five or six hours. Even among individuals in the same age group, some people need more or less hours of sleep than others to be at their best. So how much sleep do we really need?

We’ve broken down the latest sleep recommendations for children and adults from the National Sleep Foundation.

Newborns (0-3 months)

Newborns awaken every few hours to be fed, changed and cared for, and then they go back to sleep. Newborns should sleep for approximately 14 to 17 hours a day, with a minimum of 11 and no more than 18 hours. Sensitivity to light and darkness begins to develop at six weeks, and by three to six months, most newborns sleep more at night than in the daytime, although they continue to nap repeatedly throughout the day.

Infants (4-11 months)

Infants need 12 to 15 hours of sleep, with a minimum of 10 and no more than 18. Most infants begin to sleep through the night by 9 months of age. Their sleep time should include one to four daytime naps of one-half to two hours.

Toddlers (1-2 years)

Toddlers should have 11 to 14 hours of sleep each day, with a minimum of nine and no more than 16. At 18 months, their nap time can be reduced to once a day for one to three hours in length.

Preschoolers (3-5 years)

Preschoolers do best with 10 to 13 hours of sleep, with a minimum of eight and no more than 14 hours. By age five, most children will no longer need a midday nap, but they may benefit from quiet time to rest.

School-Aged Children (6-13 years)

In spite of pleas to stay up late, school-aged children should be in bed for nine to 11 hours a night, with a minimum of seven and no more than 12 hours of sleep. Promote good sleep habits by turning off the TV and electronics at least one hour before bedtime and limiting caffeine and energy drinks.

Teenagers (14-17 years)

Teenagers require eight to 10 hours of sleep per night, with a minimum of seven and no more than 11. Enforce a consistent bedtime, even on weekends. Missing even an hour a night can result in a big deficit by the end of the week, and sleep binging on weekends will not help to make up for it.

Young Adults (18-25 years)

Young adults are still developing physically and mentally and are often more active than older adults. They need seven to nine hours of sleep each night, with no less than six and no more than 11.

Adults (26-64 years)

Adults need slightly less sleep than their younger counterparts, but seven to nine hours is still a good range, with no less than six and no more than 10. If needed, a brief “power nap” during the day can help with memory, alertness and mood.

Older Adults (65+ years)

The need for sleep diminishes as we age. Older adults should still aim for seven to eight hours, with a minimum of five and no more than nine.

Adjusting Your Sleep Time

We can adjust sleep time for ourselves and our children by paying attention to how we feel after sleeping for a certain number of hours. Some of us feel alert and chipper at the lower end of the recommended range, while others may struggle with anything less than the full recommended time.

When considering adjusting your sleeping time, consider the following:

• Do you need several cups of coffee or energy drinks to carry you through your day?
• Do you find yourself dozing off during meetings or behind the wheel?
• Are you overweight or at risk of a chronic illness?
• Can you wake up without an alarm clock?
• Are you recovering from illness, injury or a stressful experience?
• Are your children hyperactive or showing behavioral problems? Keep in mind that overtired children don’t droop like adults—they become hyperactive. Inadequate sleep can mimic ADHD, so keeping them up won’t make them sleepier. Send them to bed instead.

If you experience physical problems such as snoring, leg cramps or breathing difficulties are interfering with your sleep, talk to your doctor to see if you’re at risk for an underlying condition that may affect your sleeping habits.

Keeping these recommendations in mind, it’s important that you strive to set an example of good sleep habits for children, starting at a young age. Lack of sleep on a regular basis can affect our mental, physical and emotional health, and for children and young adults who are still developing, that restlessness can cause more serious health concerns later in life. A good night’s rest will only promote a good day ahead.