Circadian Rhythm Renovation

From a very young age I liked to stay up late. I was lucky that I had fairly permissive parents, and my dad especially would allow me to stay up, sometimes past midnight, even on school nights. My parents were divorced and I was raised in San Francisco. My dad drove a cab Thursday, Friday, Saturday, and Sunday nights. He had me on Monday, Tuesday, and Wednesday nights. When I stayed with him we would eat dinner late, usually a big meal at a Chinese restaurant, and then go catch a movie. Then we’d come home and watch Monte Hall’s “Let’s Make a Deal” which came on at 11 or 11:30 pm. After that there was nothing but news, and I’d fall asleep in the wee hours as the reports of international happenings droned on.

My affinity for late nights only increased as I got into high school. Whether I was working on something for school (I always started everything the night before it was due, no matter how big the project), out partying with friends, or…


[Pardon me. I need to insert an aside here. My brain is misbehaving. As I think back on my teenage years, my brain keeps telling me I was on the computer late at night. Or on my smartphone. I can see myself, in my mind’s eye, staring into a screen. But this was before the days of internet access and certainly before the days of smartphones. We had one computer in our house that required entering a C:/ prompt command and was barely functional as a word processor for typing in a rudimentary English paper. Our house telephone had a cord and was affixed to the wall. So why can’t I think of how I spent my time in the wee hours of the night before these technologies were a part of my life? Why do I keep imagining myself as a teenager sitting in front of my laptop? I didn’t get my first laptop until my thirties! WEIRD. What did I do late at night back then? Was I reading? Listening to music? Talking on the phone? The one with the cord? Near the wall? What on Earth was I doing??? Certainly I was eating. No doubt about that. Eating is timeless.]

In any case, whatever non-technological, homespun activity there was back then, I was doing it, and I liked to do it late at night.

In my twenties, my night-owl habits became a problem.


I couldn’t get up before noon. Left to my own devices, I would stay awake until 2-4 a.m. every night, and sleep until 2-4 p.m. every afternoon. That’s right. 12 hours of sleep. (Did I mention I was clinically depressed?)

Those who knew me back then can testify that this is not an exaggeration.

Then, at the age of 28, I was taught the principles of Bright Line Eating™, and I started eating just three meals a day.

I was taught to eat breakfast at breakfast time, lunch at lunch time, and dinner at dinnertime.

Novel concept.

I soon discovered that, when I couldn’t eat anything after dinner, I would run out of steam around 9 or 10 p.m. and want to go to bed.

I wanted to go to bed so it would be morning already and I could eat breakfast.

Within about a month’s time, it became natural for me to get up at 6 a.m. and go to bed by 10 p.m.

Before long I was rising even earlier, to complete 30 minutes of morning meditation before breakfast.

And then a really weird thing happened.

I started waking up before my alarm. The alarm that was set for 5:30 a.m.


These days, I sleep in once in a blue moon, and “sleeping in” means sleeping until 7 or 8 a.m.

It’s actually hard for me to do. Usually, my body won’t stand for it.

And I never, ever have to hit “snooze.”

My alarm is set on the “feather light” tone at a volume of 1 (the options range from 1-10), and at the first sound of those feather light tones, I’m instantly up.

When it’s morning time, I am AWAKE.

This morning my alarm was set for 5, and I woke up at 4:37 a.m.

Naturally. And bounced out of bed.

I don’t know about you, but given where I come from, this seems all very strange to me.

Totally mysterious.

Baffling even.

In my introductory psychology classes I lecture about circadian rhythms and the story goes something like this: Circadian rhythms are 24 hour biological cycles that affect things like sleep-wake patterns, hormone release, cognitive functioning, and body temperature. There are specific genes associated with circadian rhythms. Some people have a cycle that’s naturally a little longer than 24 hours, and these people are night owls. Other people have a cycle that’s naturally a little shorter than 24 hours, and these people are morning larks. The circadian rhythm is reset every day through light (typically daylight or sunlight) that affects the suprachiasmatic nucleus (SCN) of the hypothalamus and triggers the release of melatonin.

But the evidence of my life indicates that my circadian rhythm probably wasn’t inborn or genetic—it’s been completely altered by environmental cues.

The environmental cues on the end of my fork.

I’ve wondered for years how it could be that something so simple as changing my eating patterns could have had such a dramatic impact on my biological clock. Can establishing set mealtimes really turn someone from a night owl into a morning lark?

Last week, I read an article in the New York Times that suggests that scientists have been investigating this very question.

The article itself implies some ideas about weight loss that I frankly don’t agree with. It argues that health will be preserved if you eat crappy foods, so long as you restrict your eating to 12 hours a day. I don’t think that will work if the 12 hours you pick to not eat are, say from 3 a.m. to 3 p.m. Lots of people do that. They gobble down food into the wee hours of the night and eat so much junk that, come morning time, they never “feel like eating breakfast.” So they fast all day, and then start the feeding frenzy again the next night. They are some of the most overweight people among us.

Not eating for 12 hours only works to help you lose weight if those 12 hours are, say, from 6:30 p.m. to 6:30 a.m.  That’s a big “if.”

That’s my hypothesis, anyway.

In any case, what struck me about the article was not so much its main thesis, but a tiny little quote at the very end, by professor Satchidananda Panda of the Salk Institute. According to Dr. Panda, “Meal times have more effect on circadian rhythm than dark and light cycles.”

Wow. There it is.

The article doesn’t provide a citation for this assertion, but I’ll be following up to find out what research has been done on this topic so far.

In the meantime, I’m left with two overarching conclusions.

First, never underestimate the breadth and scope of knowledge that science has yet to uncover. What we think today, we may unthink tomorrow.

Second, for many of us, healthy eating is what Charles Duhigg calls a keystone habit. Put it in place and watch the benefits ripple throughout your life.

With love,


P.S. – What does your eating affect in your life? Scroll down and leave a comment! I do my best to read every one.


  1. Kimberly m joslin

    How does one deal if they work shift work. I want to try this but I work a rotating shift.

    Reply ·
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  3. Terri R

    This is well and good for “normal” people but what about those of us who work shift work? I work rotating shifts for six week stretches each of: days-0800-1600 / p.m.-1600-0000 / graveyard-0000-0800. There is also the “relief” shift of one day shift, two p.m. shifts, and two graveyard shifts each week. Circadian rhythm is pretty much out the window.

    Reply ·
  4. Mary

    Very good info, I appreciate your devotion to such a difficult task. Interested in learning more.

    Reply ·
  5. Sandy

    I am in the investigating stage of BLE. I was sold on it until I went to register for the Boot camp and I had no idea how high the price was! I have been looking for a scientific program for months. I figured with today’s advancements in brain/body research (which I love to read about), there would have to be a more scientific approach to weight loss. So your program, eat 3 meals a day and that’s it, doesn’t seem very “scientific”. Also I’m a floor nurse in a hospital working 12-hour shifts. I can’t just leave a patient at an exact time and go eat a meal. How would I ever fit this strict program into the days I work my job? I have failed at many other programs because they are too strict and I can’t fit them into my lifestyle or I was starving all day or feeling very fatigued or if I “cheated” it was all over.
    So please – sell me. Point me to what I need to learn about your program that makes it any different. Also, I don’t mind working out a few days a week. I try to do that anyway and I like to do , weights because I know its good for me at age 52.
    Thank you

    Reply ·
  6. N LoSasso

    My boyfriend is such a morning person and I’m a true night owl. It has caused problems in our relationship. Its caused me problems my whole life with school and jobs. I would love to actually be up early with him and have the day instead of missing half of it as I crawl out around 10am. I will have to reread this article several times to understand my late night bingeing, not only presents all the obvious repercussions but is even causing me to miss out on the best times of my life. Good grief who would have known what we eat, how we eat, when we eat… is so much more than we’ve ever been taught !!! I’m voraciously reading as much as I can, as fast as I can, Susan !! Grateful-in-CO. XXO

    Reply ·
  7. Ferne

    Very good article! We are linking to this particularly great article on our site.

    Keep up the good writing.

    Reply ·
  8. Lynda D. Hahn

    So very interesting. Something I really thought was “just me”!
    I have for so long now been an early riser, which drives my husband crazy! We are total opposites. I Will get up at the very Latest by 6am. But I get so much done, my energy levels along with my OCD kicks in. No, I don’t have a diagnosed OCD, it’s a spouse/self diagnosis! I cannot, no matter how much I try, sleep in! I am also in bed by 10pm. Seems this Circadian Rhythm is set in me!
    Thanks Susan, it’s great having a name for it. Love you and your wonderful work.

    Reply ·
  9. Dianne

    Very interesting, Susan. I remember reading (somewhere) that the Sumo wrestlers of Japan get to be their large size because they are fed their largest meal before going to bed.
    Love the work you are doing.

    Reply ·
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  12. Jade

    This is my 36th day of BL eating. I have always been an early bird. What I have noticed since starting eating three healthy planned and committed meals is that I don’t have that sleepy period in the afternoon where I feel I need a nap. In fact I couldn’t nap if I wanted to. I have too much energy! What a gift, one day at a time.

    Reply ·
  13. Marianne Marsh

    Bright Line Eating affords me more productivity as well. Before BLE, I spent much of my mental and emotional energy on what I would eat, what I wouldn’t eat, when I would eat it, how fat it would make me, ad infinitum. With BLE boundaries around my food, it feels as if I have more room in my brain for other things! Thus I am better able to focus on the issue at hand because I’m not thinking about eating.

    One other significant benefit of BLE I’d like to mention is connected to my health. I’ve been a chronic asthmatic since I was 10 (I’m now 57). While I’m not asthma-free, I can’t remember the last time I had to use my inhaler. Happy, thin, and breathing free!

    Reply ·
    1. Susan

      Wow, Marianne, that’s fabulous! I have family members who have asthma, and to not need to use an inhaler is truly a great gift. Huzzah!!!

      Reply ·
    2. Beverly Alexander

      My husband has had asthma since he was in his twenties. I remember several trips to the emergency room in the middle of the night, accompanied by our three children in pajamas. I finally got him to see an allergist and take medication – but he still sometimes (not nearly as often) had asthma attacks. Fast forward to 7 years ago. Changed my/our diet to vegan, based mostly on Prevent and Reverse Heart Disease by Caldwell B. Esselstyn, Jr., MD. No more asthma attacks. Ever.

      Reply ·
  14. Linden Morris Delrio

    Productivity is where I notice it the most. I get way more done in a wiser fashion, when I am eating in a BLE way: i.e three healthy meals a day. Period. When I am “all over the map” with my food and eating habits, my productivity slows to a creep

    Reply ·
    1. Susan

      I totally agree, Linden! The increase in productivity is astounding. I frequently get asked how I “manage to do it all,” and the only response I have is Bright Line Eating. It’s ironic, because people often worry that eating this way TAKES time (time to shop, time to prepare food, time to chew), but in reality, eating this way CREATES time. Not eating in-between meals frees up a lot of time, but the sheer power of the mental clarity that comes from eating a healthful diet can only be believed when it’s experienced.

      Reply ·
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