One summer day in 1962, 23-year-old French geologist Michel Siffre climbed into a freezing cave in the Alps for an experiment most of us wouldn't try for one day...
He planned to do it for two months.
Siffre was curious about how living in near-complete darkness and isolation would affect one's sense of time. So he descended into a cave 375 feet underground to test the idea on himself. His only access to the outside world was a one-way radio to communicate with his team stationed above ground.
Siffre entered the cave on July 16 and planned to leave on September 14. But there was a catch...
As time passed, he'd have no idea what day it was. And he'd forbidden his teammates from telling him. He'd radio them each time he awoke, ate, and got ready to sleep. But under no circumstances could they tell him how much time he had left.
When September 14 rolled around at last, Siffre's team told him that the experiment was over, leaving him stunned...
He thought it was only August 20.
You see, during Siffre's two months underground, his sleep-wake cycle had drifted, settling at a little over 24 hours. That added up over time... which was why he thought he still had nearly another month to stay underground.
Siffre's bizarre experiment helped launch the study of chronobiology in humans, or how our internal biological clocks keep time.
More than 60 years later, we're still learning just how much the ordinary rhythms of our day matter. As it turns out, you don't have to live in a cave to throw your body's clock out of whack. We do it all the time...
Whether it's sleeping until noon one day and waking at 7 a.m. the next... eating dinner at 5 p.m. tonight and 10 p.m. tomorrow... or changing when you exercise or socialize... all these things change the signals your body receives from its environment throughout the day.
And according to new research, having a somewhat "boring" routine might be especially good for us as we get older...
Our Bodies Love Knowing the Time
Your body doesn't run on just one "clock." Nearly every tissue and organ system has its own circadian rhythm. Meanwhile, a group of nerve cells in your brain called the suprachiasmatic nucleus acts as the master clock coordinating the other clocks.
Light and darkness provide the strongest signals to this system. But food, exercise, stress, temperature, and social factors in our environment can all influence our circadian rhythms. Scientists sometimes call these external cues "zeitgebers," which is German for "time givers."
You can think of zeitgebers as little reminders to your body about where it is in the day...
Morning sunlight says, "It's time to get up." Meanwhile, eating lunch says, "We're halfway through the day." When those signals arrive somewhat predictably, that pattern can help keep all of your body's internal clocks working together.
In a Journal of Behavioral Medicine study from March, researchers examined 67 adults aged 68 on average. Thirty of them were considered "good sleepers," and 37 had insomnia. Participants were asked about their "behavioral-social rhythms" – or how regularly they did everyday things like sleeping, eating, working, and socializing.
The results showed that folks with more regular daily rhythms reported less pain, fewer depressive symptoms, and lower body mass indexes. And those associations remained the same regardless of whether the participant suffered from insomnia.
A 2018 study from the Gerontological Society of America had similar findings. Researchers asked around 460 older adults how often they got up, went to bed, ate meals, and did activities around the house at similar times every day.
They found that the participants with the least regular routines reported having worse physical function and more symptoms of depression and anxiety, compared with participants who had more established routines.
Maintaining a predictable daily pattern could benefit sleep, too...
A 2010 study published in Sleep that involved 96 older adults found that keeping a more stable daily routine was linked to falling asleep more quickly, having better sleep efficiency, and experiencing better overall sleep quality.
And get this: Sticking to a routine is about more than just chores...
In a 2024 study, researchers followed 103 adults between the ages of 65 and 84 for more than three weeks. During that period, the researchers recorded when and how participants interacted with other people. They found that the participants whose social interactions happened more routinely (e.g., talking to people at similar times) tended to report feeling more positive emotions and fewer negative ones.
Now, I'm not saying you're guaranteed all of these outcomes by sticking to a schedule all the time... But altogether, these studies suggest that as we get older, a little more predictability might be good for us.
How to Add Rhythms Into Your Day
You don't need to be exactly on time, to the minute, for all of these things. But aiming to stay within the same general window for your sleeping, eating, and exercising can do wonders for your health. Here are a few ideas to get you started...
Start with a consistent wake-up time. Try getting out of bed at roughly the same time each day – weekends included. Then open the curtains or, even better, step outside and bask in the morning light. (Remember, light and darkness are the most powerful environmental signals controlling your circadian clock.) As soon as I open my eyes in the morning, I do the same for my blinds. Then I make some coffee and take a short walk outside.
Schedule your mealtimes. Food intake is another signal that helps your body keep track of the day. Pick the windows of time for your meals that work best for you and try to stick reasonably close to them most days.
Attach movement to something you already do daily. I know, I know, I'm constantly telling you to move your body. And here's a trick to make it easier... Instead of thinking, "I'll exercise sometime today," add movement to something that's already part of your routine. Maybe it's a 10-minute walk after breakfast... a few squats while you heat up your food... or an evening stroll after dinner. Not only does doing this make exercising easier to remember, but the physical activity itself also influences your circadian rhythm.
Don't forget to schedule something social, too. It might be meeting up with a friend for coffee every Tuesday, volunteering on Thursdays, attending religious services on Sundays, or calling up your grandkids at the same time every weekend. You'll get the double whammy of adding a social zeitgeber to your life and staying connected to the people you care about.
Finally, don't get hung up on organizing every minute of your life. Maybe your grandkids will pop in for a surprise visit, dinner will run a little late, or you'll sleep in during vacation. Don't make sticking to a too-rigid schedule your objective – you'll get stressed out. The goal is to give your body a handful of dependable cues throughout the day. It might be boring – but it's good for you.
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Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
August 20, 2026