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Biology, Health

FitBit: 150 Billion Data Hrs Shows Sleep Hours Sweet Spot, Optimal Health Strategy

An astounding 150 billion hours of collected FitBit data from tens of millions of users indicates: 1) Aim for the sweet spot of 7.25 hrs sleep, as more or less is unhealthy. 2) Move your body throughout the day (eg. take an hour long walk every morning) and 3) get an average of 30 min of moderate to vigorous exercise 5 days a week (150 minutes of exercise/wk), 4) keep stress relatively low (do things daily to relax).

FitBit devices log the wearer’s exercise, heart rate and sleep time. They are popular in many countries and the FitBit company has amassed an impressive heart database from users over the years. From this data we can see, statistically, broken down for men vs women, that certain things are correlated with optimal health based on the measure of resting heart rate (RHR)

First, what’s the big deal with resting heart rate? It turns out that resting heart rate is a yardstick for overall health. Here is some of the evidence:

In the general population without known coronary artery disease and heart rate lowering medication, elevated RHR is an independent risk marker for all-cause mortality but not for coronary events. – NIH

Participants (n=51,936) who received a baseline medical examination between January 1, 1974 and December 31, 2002 were recruited from the Cooper Clinic, Dallas, Texas. Highest cardiorespiratory fitness (CRF) with lower mortality was found in individuals with a RHR <60 bpm. Similarly, participants with a higher RHR, >80 bpm, were at greater risk for both CVD and all-cause mortality when compared with RHR <60 bpm.- NIH

… cumulative exposure to higher RHR is independently associated with an increased risk of mortality. – Nature

In fact, a resting heart rate of more than 80 beats a minute brings a 45 percent greater risk of death from any cause. Even those with a relatively healthy RHR between 60 to 80 have an increased mortality risk (21 percent) over those with a rate below 60. A meta review of 18 epidemiological studies showed “a mortality excess of 30% to 50% for every 20 beats/min increase” in RHR.

Our RHR is regulated by the sinus node, which generates electrical impulses to regulate our heart. Regular exercise improves the heart’s efficiency.  Superbly conditioned individuals have lower RHR, usually 40 to 60 beats per minute (BPM). Tour de France cyclist Miguel Indurain had a measured RHR of 28 beats per minute, although even that is not the world record. – BioStrap

What is the lowest healthy resting heart rate that has been measured?

Daniel Green achieved the world record for the slowest heartbeat in a healthy human with a heart rate of just 26 bpm in 2014.- Wikipedia

Daniel Green, 81, could not believe it when doctors told him his heart rate had dropped to just 26 beats per minute (bpm), which is slower than even cycling hero Sir Bradley Wiggins’ at rest. Exercise enthusiast Mr Green was having a regular check-up when doctors realised his resting rate was 36bpm, before it then dropped to 26bpm and officially lower than the world record. “I go for hour-long walks every morning and do some light exercise with weights and a cross-trainer at least three times a week. – Express

Resting Heart Rate is again one of those measures that has a sweet spot. You can go too low. If your heart slows down too much you can get symptoms such as Lightheadedness or dizziness, confusion or a hard time concentrating, fainting or shortness of breath (with or without chest pain). A slow heart rate can also be a sign of some illnesses.

Bradycardia, even as low as 50 beats per minute, can be normal in athletes and other people who are physically active. In these people, regular exercise improves the heart’s ability to pump blood efficiently, so fewer heart contractions are required to supply the body’s needs.

Bradycardia also occurs in some people who have certain medical illnesses not related to the heart, such as:

  • An abnormally low level of thyroid hormones (hypothyroidism)
  • An abnormally low body temperature (hypothermia)
  • A very high blood potassium level
  • Lyme disease
  • Typhoid fever

In most cases, bradycardia in healthy, well-trained athletes does not need to be treated. In fact, in most people, bradycardia does not require treatment unless patients have symptoms that are clearly due to a slow heartbeat.


What affects resting heart rate (RHR)?

Numerous factors affect RHR, which is why regular measurement is key. Fitness, activity, gender, age, size, disease, and stress can impact your RHR, as will transient circumstances such as room temperature, body position, medications or caffeine.  Recent research shows heart rate also has a genetic component. – SciAm

Warmer temperatures cause the heart to beat faster and place considerable strain on the body. Simply put, when it is hot, the body must move more blood to the skin to cool it while also maintaining blood flow to the muscles. … Depending on how fit you are and how hot it is, this might mean a heart rate that is 20 to 40 bpm higher than normal. – HumanKinetics

How do you measure resting heart rate?

The average adult has a RHR between 60 and 100 beats per minute (bpm), while an athlete often has a rate between 40 and 60 bpm. I’ve found that you can find your pulse most easily on the underneath side of your wrist, at the base of your thumb. Turn your arm over and using your first two fingers, gently feel for a pulse on your wrist. Once you find it, feel it’s rhythmic, regular beat. Then, using a clock with a second hand or the timer on your phone, count the number of beats you feel for 30 seconds and multiply this number by two (or count your pulse for the full minute). Write down the date and the number of beats you counted each morning for the next several weeks. After several measurements, you will have established your baseline pulse, or what is your “norm.”

Here is some of the FitBit data, charts showing goals you may want to consider if you are in the process of getting healthier.


Everyone is unique and ultimately you must discover your own ideals and sweet spots, but do consider that your mind may be wrong about what it thinks your body needs. You may be sleeping the amount you do out of habit rather than because it is best for your health. If you are getting more than 8 hours sleep per night for more than a week, try an alarm clock to train the 7.25 hr sleep for a week or two and see how you feel. If you are getting LESS than 7 hours per night, there are many tips to help you sleep.

My quick summary for insomnia  or under-sleeping is:

* Eat enough during the day. Some people, such as those on low carb diets, can have trouble sleeping due to essentially bonking in the night. You need your stored 500g or so of glycogen in your liver to take your body through 7 hours of sleep without food.

The untrained individual typically holds about 400 g of glycogen stored in both the muscles and the liver, while a trained athlete can hold double that amount. This is enough glycogen to last several hours of exercise without replenishment. During exercise, the body will convert glycogen into glucose, which plays an important role in the contraction of muscles, and is the primary fuel source for most organs, such as the brain. – LiveStrong

* Establish a regular schedule. The body’s organs remember what happened yesterday at about this time and this is the reason a regular schedule for sleep and eating are optimal.

* Avoid blue light after sunset. We have receptors in our eyes that regulate our sleep cycles via hormones, etc. Use blue light blocking glasses or try reading a book at night instead of using a phone or computer.

* Take an hour walk every day. Our lymph system flushes waste from our cells into our blood system. Body movement is the pump for our lymph system, so take a walk to take out the body’s daily trash. Morning is a good time.

* Make your room a sleep sanctuary. Block all light and sound possible in your sleep room, this includes light from LED clocks, and even the little lights on power strips. Heavy curtains are a worthwhile purchase to block both light and sound.

* Practice mindfulness meditation daily. Meditation, the type where you simply observe your thoughts for 15 minutes letting them come and go without being disturbed or captured by them, is one of the best things you can do for great sleep. With a meditation practice as part of your life, when it comes time to sleep, you will naturally know how to mentally let go and drift off. If you wake up an hour too early, just lay in bed and meditate for an hour.

Good luck and good health,






About Xeno

E pluribus unum.


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