(CNN) American teenagers aren't getting enough sleep these days, and author Lisa L. Lewis refuses to snooze on the issue anymore.
Lewis, a mother of two, helped spark the first law in the nation requiring healthy school start times for adolescents — a law that will be put into action in California later this summer.
Her new book, "The Sleep-Deprived Teen: Why Our Teenagers Are So Tired, and How Parents and Schools Can Help Them Thrive," was released June 7 and details so many things parents and caregivers need to know about teenagers and sleep.
Lewis shared why sleep is so important for teenagers, how much sleep teens should be getting, and why they need to sleep more than adults. She touches on all the factors that can negatively affect teen sleep: technology, gender, sexual identity and socioeconomic status, to name a few.
CNN recently talked with Lewis to discuss her work, and to learn more about how parents and caregivers can get their children more sleep.
This conversation has been edited and condensed for clarity.
CNN: What prompted you to write a book about teens and sleep?
Lisa Lewis: The whole issue of teen sleep and school start times hit my radar when my oldest kid, who is now in college, entered high school. At that point, the school started at 7:30 a.m. And I just knew that was much too early. I was driving him to school at that point, and every morning I'd look over and see he was not very awake. Every afternoon he was coming home really worn out.
I wanted to know why school started so early. What I found was that I had tapped into a much bigger issue. That same month, the US Centers for Disease Control and Prevention released its baseline report on school start times, which came on the heels of the American Academy of Pediatrics policy statement on the same subject. Their recommendations were that middle school and high school should start no earlier than 8:30 a.m. That's what got me involved.
CNN: So why do teens need so much sleep?
Lewis: At the onset of puberty, teens have a circadian rhythm shift, and their body clocks shift to a later schedule. It also connects to the release of melatonin, which is what primes our bodies to sleep. When kids become teenagers, melatonin begins to be released later than it used to. That means teens are not ready to fall asleep until 11 p.m. Because the same melatonin does not recede until later, teens end up wanting to sleep in more than they used to.
CNN: How much sleep should teens be getting?
Lewis: Most teens should get between eight and 10 hours, according to the National Sleep Foundation. The amount of sleep we need throughout our life span does change, though. When you look at kids up to age 13 — so, tweens — they need nine to 11 hours. The recommended range for adults is seven to nine hours. There are some teens and grown-ups for whom less than the prescribed amount will be fine. There also are some teens for whom 10 hours will be what they need. Sadly, many of our teens are not getting even the minimum of eight hours. Data from the CDC indicates that in 2007, only 31% of teenagers were getting eight hours or more. By 2019, that number was down to 22%. We're in a teen sleep deprivation epidemic.
CNN: What are the ramifications of teens not getting enough sleep?
Lewis: Sleep for teens is an emotional buffer and provides emotional resiliency. Teens are going through a major phase of brain development, and sleep is where a lot of that development happens. In the classroom, students who are asleep are not learning. Students who are there and not fully awake are not learning well. Sleep deprivation limits students from acquiring information, impedes the retention of the information, and hinders the ability to retrieve that information.
Various studies have indicated that when schools shift to later start times, they see improvements in attendance and graduation rates go up. With sports, sleep enhances performance; plus teen bodies release growth hormone, which heals injury when they sleep, so being well rested is a competitive advantage. In general, well-rested teens are happier and healthier and do better in school. They are more emotionally resilient. And they are easier to live with.
CNN: Beside early start times, what are some other external factors that can disrupt teen sleep?
Lewis: Stress is a huge one. If your kids can't get to sleep before 11 p.m., you need to look at whether they are overloaded or overscheduled. Technology is another factor. If you have a teen who is up until 1 a.m. or 2 a.m. playing video games, that is cutting into their sleep time, too. There are other factors. Menstrual cramps can impact sleep. We know that sexual- and gender-minority teens sleep worse than their counterparts, as do teens of color. There are other factors, too, like living in crowded conditions, or where it's noisy or where teens don't feel safe, that can impact sleep.
CNN: How do you think the chaos of the pandemic years has impacted teen sleep?
Lewis: I think the biggest issue is mental health. We have seen every major group sounding alarms about teen mental health. Back in December, the US Surgeon General issued a special advisory on teen mental health. The CDC released new data in April showing that mental health has worsened in teens.
CNN: How can parents and caregivers convince teenagers they need more sleep?
Lewis: Lecturing them doesn't have the desired effect. Having a conversation is more helpful, especially if it's an ongoing conversation. Model good behaviors, like no tech use within one hour of bedtime. Teach them about things like a wind-down routine. Our brains are not like computers — you don't just turn it off and hit the pillow and go to sleep. One thing that's important is not to force any of it.
CNN: At what point did your project expand to advocacy?
Lewis: They went hand in hand. After those big reports came out, I wrote an op-ed for the Los Angeles Times the following fall about why schools should start later in the morning. That piece was read by California State Sen. Anthony Portantino, who had it on his radar as well. He started looking into it and introduced a bill about school start times in February 2017. I reached out to a national nonprofit named Start School Later and I started a local chapter. As the bill advanced, I ended up testifying in front of the state (Assembly's) education committee. It was a lengthy process that culminated with Gov. Gavin Newsom signing the bill into law in 2019.
CNN: Why is this new law significant?
Lewis: The new law goes into effect July 1, and it's the first of its kind in the nation requiring healthy secondary school start times. It specifies that for public and charter middle schools, start times can be no earlier than 8 a.m., and for high schools, start times can't be earlier than 8:30 a.m. Similar laws in other places have proven to be successful. To this point, the largest city to change its start times is Seattle; they did it in 2016. The city did all these surveys before and after that change, and they learned students got an extra 34 minutes of sleep on school nights once the start times were moved back. That's huge.
CNN: What are the big questions you'll be asking next?
Lewis: As of right now, California is the only state that has enacted a law of this scope. That leaves quite a bit of room to work with other states out there. As of right now, both New York and New Jersey have active bills on this topic, but no other state has passed a law like this. There is a tremendous opportunity to look at doing this in all the other states; teen sleep deprivation is not just a California issue. This is something I will be focusing on for quite a bit.