I’m a sleep expert — here’s how many hours of rest you need at every age

From the cradle to the grave, our sleep needs change.

Fresh from the womb, newborns spend the majority of their days in slumberland, a snooze schedule that tapers off as growth decreases throughout toddlerhood and adolescence.

Both puberty and old age drastically affect sleep. And while teens sleep often and late, seniors hit the hay in the early evening. All of this suggests that sleep requirements are an ever-shifting spectrum, with this man, who claims to sleep 30 minutes a day, falling on the extreme end.

But where do you fall on the slumber scale, and are you getting the sleep you need?

Babies

In their first year of life, babies triple their weight, and abundant rest supports these gains as the growth hormone is released en masse during slow-wave sleep. From birth to three months, babies sleep 14 to 17 hours of the day, and their growth is equal parts physical and cognitive.

“There are a lot of new neural connections forming and a lot of new learning going on,” Dr. Yi Cai, director of sleep surgery at the Columbia University Irving Medical Center, told TIME. “Everything’s new, and that’s a prominent driver of sleep needs for that age.”

From four to twelve months, babies begin to sleep less as they adopt and adapt to a circadian rhythm.

Toddlers

Sleep needs continue to drop as babies cross the threshold into toddlerhood and growth rates slow. Children need 11-14 hours of sleep from one to two years old and 10-13 hours from three to five.

Some of this sleep is distributed to nap time, a doze designation that decreases with age.

According to the National Sleep Foundation, by 18 months, most toddlers are averaging one nap a day, lasting one to three hours. From three years on, nap requirements vary from child to child, with some doing away with them altogether.

“We have some kids that are dropping the nap much earlier than other kids because it’s affecting them at night,” Joshua Tal, a New York-based sleep and health psychologist, told TIME. “Other kids have very predictable naps.”

Tal explains that an active imagination and the fears that come with it can begin to affect sleep patterns among this age group.

Teens

From six to twelve, nap time typically ceases, and sleep needs dip to nine to twelve hours per night.

Puberty, however, brings shifting needs and an onset of challenges.

It’s recommended that teenagers get eight to 10 hours of sleep each night. Many miss the mark, struggling to get their shut-eye due to circadian rhythm delay, later melatonin onset, and higher rates of alertness in the evening, all predisposing them to later bed and wake times.

“A lot of teenagers just have a delayed sleep drive,” Cai explained. “That’s why some teens run into problems with early school times, where they may not get the sleep they need to be up in time for school, and then they might need to catch up on their sleep during the day when they’re back home.”

Research suggests teens who routinely nap for 30 to 60 minutes per day have improved attention, nonverbal reasoning ability, and spatial memory. Thus, the solution to sleep deprivation may rest (pun intended) in designated, school-sanctioned naptime.

Adults

When we reach the point of adulthood, Tal explained that the body is in “maintenance mode.” This growth plateau is mirrored in reduced sleep needs, with seven to eight hours being the sweet spot.

If you need more, Tal warns you might be suffering from a sleep disorder such as sleep apnea or hypersomnia and should seek medical attention.

As with all things, timing is everything, and recent research suggests hitting the hay by 1 a.m. can lower your risk of developing mental and behavioral conditions such as depression and anxiety.

For those looking to improve the quantity and quality of their sleep, experts suggest evening exercise and a diet rich in fruits and veggies.

And if you’re looking for another reason to hit the snooze button on Saturday, researchers say sleeping in on the weekends can cut your risk of heart attack. If you’re hoping to boost creativity, experts say there’s no shame in napping.

Seniors

After 65, the production and release of melatonin reduces, resulting in less and lighter sleep. As the body ages, urination can become more frequent, disrupting sleep patterns.

Advanced age is also associated with an advanced Circadian rhythm that causes the body to crave an earlier bedtime and wake up, but seven to eight hours should still be the aim.