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How I Use Lumen to Track What and When I Eat for Better Sleep


Written by Dr. Michael Breus

photo of Dr. Michael Breus holding the Lumen

There is a very strong correlation between food, digestion, and sleep. Eating at the right time can facilitate a night of good and restorative sleep. Eating the wrong food or at the wrong time can cause poorer sleep quality.

A new device called Lumen has set out to help consumers solve the conundrum of knowing what and when to eat before bed.

Until now, I’ve always told people to stop eating two to three hours before bed and if they’re going to have a snack, make it a high protein snack. But Lumen gives you a much more scientific look at your food consumption and how it is impacting your overall energy levels.

Lumen is a small device that measures the amount of carbon dioxide in your breath. It’s simple to use. Turn on the device and then inhale through the mouthpiece, hold your breath for 10 seconds, and then exhale through the mouthpiece. You’ll generally do that one to two times, several times a day.

What I discovered is that doing it more often gives much better results. The connected app lets you know if you are in carb burning mode, fat burning mode, or somewhere in between. Lumen reports on a scale of 1 – 5. On the scale, 1 and 2 indicate you are burning mostly fat, 3 means you are burning fat and carbs, and 4 and 5 let you know you are burning mostly carbs.

There isn’t a “good” number or a “bad” number, as your body should naturally be moving between carb and fat burn. The important thing is to use the right fuel at the right time, which is key to achieving metabolic flexibility.

Ideally, your body will use carbs throughout the day, according to Lumen. These carbs support your daily activity, whether working out or simply going throughout your day-to-day routine. Then, in the evening, when you are resting, your body should shift into fat-burning mode and use fat as fuel to support healthy rest.

The science behind this approach is pretty convincing and from what I’ve discovered, can be really interesting when you combine Lumen with your chronotype.

How Lumen Can Help You Understand What to Eat and When Based on Chronotype

If you’ve read my book, The Power of When: Discover Your Chronotype or taken my Chronotype quiz, then you likely already know whether you are a Lion, Bear, Wolf, or Dolphin and also have some idea of the ideal times to do things throughout the day. If you haven’t read the book or taken the quiz, now is a great time to learn a little more about yourself.

My experience with the Lumen has been very enlightening. I discovered how challenging it is for me to stop thinking of food in caloric terms and start thinking of food in terms of macros and timing. The videos in the app were particularly helpful for me to shift my mindset.

I discovered that as a Wolf chronotype, I prefer to eat much later in the evenings, as late as 7 or 8 p.m., then I will snack until 10 p.m., and go to bed around midnight. When I do this, I almost never wake up with anything lower than a 3, but often I’m at a 4 and occasionally higher. So using guidance from the Lumen app, I tried a few different things:

  1. I tried changing what I was eating. I must admit, I have a bit of a sweet tooth, and it’s easy to find high-sugar carbs in the “snack drawer”, especially when my kids are home. So I opted instead for veggies and small amounts of fruit. This certainly seemed to help me move more from the 3-4 range in the a.m., to the 2-3 range, and supported my body in moving through a better range of fuel use than simply running off of carbs all day.
  2. I stopped snacking by 8 p.m. I will tell you that this has been one of the bigger challenges I’ve had recently, but with some serious discipline and regular feedback with Lumen measurements, I was able to break my habitual eating in front of the television. When I did, sure enough, I was able to wake up more consistently as a 2, and even had one time when I reached a measurement of 1 upon waking.

What Lumen Taught Me About Fasting and My Chronotype

I’m a fan of intermittent fasting. I don’t endorse it for everyone, but it does work well for me. The data I was getting from Lumen caused me to look at the length of my daily fast.

To be honest, I’m super busy in the mornings and I hate to eat breakfast. It’s easy for me to have a fasting cardio workout, and then forget to eat until 2:30 p.m. What I learned from my Lumen data and their videos is that my body may actually break down my muscles for protein if I fast too long, so I went back to the data and experimented with my fasting window. I was able to change to my Mesomorph body type fasting schedule (I am a Medium-Wolf) and fast for 14 hours and feed for 10, which optimized my nutritional flexibility.

If you are interested in learning your body type-chronotype mix and increasing your daily energy levels, read my new book, Energize! I dive deeply into the connection between chronotype, body type, and how to maximize your daily energy output as well as sleep. Add in Lumen and you have a powerful tool for not only energy, but also restorative sleep.

Can Lumen Help You Lose Weight While You Sleep?

Lumen is a very powerful tool in understanding how your body uses energy. You can track everything from how food impacts you to how your body responds to stress, exercise, meditation, and even saunas!

I had several people on my team use the Lumen over a period of about eight weeks and the weight loss ranged from 8 pounds for a 40-year-old woman to over 30 pounds for a 57-year-old man. Interesting side note, Lumen can also track the menstrual cycle, so you are able to see how hormonal shifts throughout the month impact your body’s use of fat and carbs. You’ll have much more precise data to help you fine-tune your nutritional needs.

By looking at their data in Lumen and by reviewing their sleep data, we were able to adjust their eating habits and sleep schedule to match their chronotype and the results were phenomenal for them. Of course, I’m not saying that you’ll lose weight if you use Lumen, but if you follow the data, you may find ways of optimizing your nutritional inputs and workouts in a way that best supports your body and chronotype.

I’m a data geek, so I look forward to continuing to use Lumen and seeing what else I can learn about myself. I’m also going to start using it more with clients who are trying to lose weight or who suffer from high cortisol in the morning.

To be completely transparent, there were a few things missing in the app for me. It isn’t always intuitive or easy to use and their overall learning organization could be better, but they continue to improve these things daily. I think over the coming months, the app will improve greatly and make the device even more user-friendly.

If you are looking for a scientifically validated way of collecting data that can very positively impact your energy and sleep, I recommend giving the Lumen a try. I think you’ll find the information very useful when you combine it with your chronotype timing.

I don’t think there is a single one of us that can’t use a little more energy or a better night of sleep. Who among us wouldn’t want to know the best time to eat the best food for the activity we are going to undertake? Lumen gives you easy access to the data you need in a stylish, well designed device that can easily travel with you wherever you go. It can help you make better decisions every day that will help you optimize your nutrition, sleep, and energy.

About The Author

Dr. Michael Breus

Clinical Psychologist, Sleep Medicine Expert

Michael Breus, Ph.D is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. He holds a BA in Psychology from Skidmore College, and PhD in Clinical Psychology from The University of Georgia. Dr. Breus has been in private practice as a sleep doctor for nearly 25 years. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is also the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan, Good Night!, and Energize!

  • POSITION: Combination Sleeper
  • TEMPERATURE: Hot Sleeper

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