The Second Leading Cause of Death After Smoking Isn't What You Think
Dr. Saema Tahir on sleep deprivation, the 3am wake-up, and what chronic exhaustion is quietly doing to your health.
In December 2025, researchers at Oregon Health & Science University published a study that should have been front page news. Across more than 3,000 U.S. counties, spanning six years of CDC data, they found that insufficient sleep — defined as fewer than seven hours a night — is the second strongest predictor of reduced life expectancy in America. Second only to smoking. Ahead of obesity. Ahead of diabetes. Ahead of physical inactivity.
Even the lead researcher didn’t see it coming. “I didn’t expect it to be so strongly correlated to life expectancy,” said sleep physiologist Andrew McHill, Ph.D. “People really should strive to get seven to nine hours of sleep if at all possible.”
And yet sixty percent of American adults aren’t getting enough sleep. Most of them know it. Most of them have decided to live with it anyway.
We’ve normalized exhaustion in a way we haven’t normalized any other health crisis. Nobody brags about skipping chemotherapy. But we brag — or at least quietly accept — running on five hours, waking at 3am and staring at the ceiling, dragging ourselves through the day on caffeine and willpower and the vague promise of catching up on the weekend.
We call it busy. We call it adulting. We call it just how things are right now.
Dr. Tahir calls it a crisis.
I asked her to come on Body Intelligence because I wanted to understand something I’ve been experiencing myself. I’m in my 40s, and for the past couple of years I’ve been waking up at 3 or 4am — wide awake, heart going, mind already running — and not being able to get back to sleep. I assumed it was stress. The company, my daughter, the mental load that doesn’t fully power down even when everything else does.
But the more I looked into it, the more I realized: this isn’t just stress. For a lot of women in their 40s, this is the body changing. Perimenopause — a word that is finally being spoken out loud, in doctors’ offices and on podcasts and in group chats — disrupts sleep in ways that are real, hormonal, and almost entirely under-discussed. The 3am wake-up isn’t a character flaw. It’s a signal.
Dr. Tahir helped me understand what that signal actually means. And what it’s connected to.
In this episode, she gets into why waking at 3am is not what most people think it is, how many people who believe they have anxiety are actually severely sleep deprived, and what one night of poor sleep is doing to your body that nobody is talking about.
This conversation shifted something for me. Not in a dramatic way. In the quieter way that good information tends to — where you finish listening and realize you’ve been ignoring something important for a long time, and you’re ready to stop.
Your body is always listening. Care better.
Watch our full conversation with Dr. Saema Tahir here:
Body Intelligence explores the rituals, philosophies, and conversations helping us care better in modern life.