A Scientific Way to Get "In Touch" With Your Heart – Part 1

Written by Anil Bajnath, MD
Posted September 28, 2021

Dear Longevity Insider,

There's a new technique in the field of biofeedback that can help provide a more accurate picture of your physical and emotional state. Meet heart rate variability.

Heart rate variability (HRV) is thought to be originally discovered by K. Grinberg back in 1896, but was not researched until the 1960s. Heart rate variability is a measurement of the time between heartbeats. It can be measured in milliseconds, which are 1/1,000th of a second. HRV is measured by your heart's response to breathing patterns. As you breathe in, your body absorbs oxygen and nutrients that allow the lungs to release carbon dioxide when you exhale.

As the body absorbs oxygen, it sends an electrical signal to the heart muscles to contract. This contraction is what pushes blood throughout your body via the circulatory system. During exhalation, there is less pressure on your heart since no new air comes in with each breath (and you exhale carbon dioxide).

A low HRV value means that it takes longer for the heart to relax and fill with blood between beats, causing reduced circulation throughout the body. 


Sleep is critical to our overall health.  Not only does our body use this time to repair itself, but it is also an opportunity for the brain to go through stages of mental development. The average adult sleeps 7 to 8 hours per night. However, not all sleep is created equal. There are four stages of sleep and two types of sleep: rapid eye movement (REM) sleep and non-REM sleep (which has three different stages). 

  • Stage 1: This stage is non-REM sleep. It is described as a light sleep, and you can be lightly stimulated without waking up. Additionally, your brain waves begin to slow down compared to their daytime activity. 
  • Stage 2: This stage is a deeper non-REM sleep. It is more difficult to be woken up during this phase, you brain waves further slowdown, and your body temperature begins to drop.
  • Stages 3: In these final stages of non-REM sleep, there are very slow brain waves called delta waves.  
  • Stage 4: REM Sleep. REM sleep is when your eyes move rapidly back and forth behind your closed eyelids, where you are in a deep sleep but dreaming.

HRV is very key when it comes to evaluating sleep quality. In fact, HRV has been successfully used to screen people for possible referral to a Sleep Lab. Typically, an individual's heart rate will vary the most while awake and then decrease at night during REM sleep. In non-REM sleep, HRV will begin to decline as your heart rate slows down. In REM sleep, however, HRV begins to pick back up again because it is a very active time for the body, and you have a faster heart rate. 

Research has shown that an individual with a low HRV value may have a hard time transitioning from being awake to entering deep REM sleep because their nervous system won't be able to relax between breaths.

This may be one reason why those with a low HRV might have difficulty sleeping or even feel tired during the day. An individual with a high HRV will most likely have an easier time transitioning from wakefulness to sleep, and will also maintain their deep REM sleep throughout the night.

I used to have trouble sleeping. Frankly my sleeping architecture was just a mess. This is the only thing that got me through. I slept like a baby!

To your longevity,

Anil Bajnath MD
CEO/Founder, Institute for Human Optimization
Chief Medical Officer, Longevity Insider HQ