What is the HRV for sleep health?

Simply put, it is heart rate variability that is strongly related to sleep quality. It refers to the slight time difference between heartbeats during sleep. It is currently one of the most core non-invasive reference indicators for evaluating autonomic nervous system status during sleep.

It may be a bit counterintuitive to say that our heartbeat is never completely uniform like a clock. Even if you are lying motionless and sleeping deeply, the interval between two heartbeats may differ by tens of milliseconds. These subtle fluctuations are the core of sleep HRV. I once met an Internet operator who was still dizzy after sleeping for eight hours for half a month. I checked his smart watch monitoring data and found that his HRV during deep sleep was nearly 40% lower than the health average for the same age group. When I asked him, I found out that he checked his work group for half an hour every day before going to bed, for fear of missing out on needs. Even when he was asleep, his sympathetic nerves were always stretched, and his body was not in a state of repair at all, but he was tired even if he didn't sleep.

However, there are now different opinions on the reference value of sleep HRV in the industry. Many health bloggers will directly equate "high sleep HRV" with "sleeping well", but most clinical sleep doctors do not recognize this absolute judgment. For example, anxiety patients with autonomic nervous system disorders may experience abnormal and large fluctuations in HRV even if they are not awake all night. Conversely, some people are born with a lower HRV baseline than ordinary people. As long as they wake up in good condition, there is no need to worry about the numerical value.

In fact, you can understand HRV during sleep as the body's "sleep background operation log". When you wake up, you may not remember whether you have dreamed or whether you were half-awake in the middle, but these subtle neural fluctuations will be recorded by HRV. If the HRV trend throughout the sleep cycle is stable and the value of the deep sleep period remains high at your personal baseline, it basically means that the quality of your sleep was good. When I usually adjust sleep plans for users, I rarely use HRV alone as the only criterion. I usually look at it together with somatosensory indicators such as fatigue after waking up and concentration during the day. After all, your own physical feeling is the most accurate way to determine whether your sleep is good or not.