Sleep. Most of us love it and can't get enough of it. Some of us see it as getting in the way of doing other "more important" things. Modern society has almost conditioned us into considering it a necessary evil. Popular Jon Bon Jovi and The Cure songs even proclaim that sleep will come "when I'm dead."
Happily there is now a case for the importance of sleep. Thanks to the tireless (excuse the pun) research of sleep scientists, we now have a much better understanding of the factors that prevent us from falling asleep (blue light, stress, shift work), the dangers associated with chronic sleep deprivation (increased risk of diabetes, heart attack, stroke, cancer, obesity, Alzheimer's disease, poor decision-making) and how much sleep we need.
The next frontier is understanding the quality of the sleep we do get.
The main method of assessing sleep quality is polysomnography, also known as a sleep study. Sleep studies record brain waves, blood oxygen levels, heart rate and breathing, as well as eye and leg movements. Outside of the sleep clinic, new technologies have allowed us alternative, cost effective and more consumer friendly methods of understanding our sleep.
There has been a recent proliferation of phone-based apps and wearable devices that help us track our sleep, but these are almost invariably based on the amount of movement a person makes while asleep. Tracking sleep quality through movement patterns can be helpful in gaining an understanding of how we sleep, but it has its limitations and can be fooled. For example, if you get really drunk and pass out for 8 hours, your FitBit might presume you had a great night of sleep.
More detailed than movement pattern-based systems is assessing heart rate variability (HRV). HRV is the difference in the length of time between consecutive heartbeats and is measured in milliseconds. If your heart beats in a consistent pattern, like a metronome, with identical time between heartbeats, then your body is stressed. If your heart beats with a more random pattern of time intervals, then your body is resting and recovering. HRV is controlled by the Autonomic Nervous System (ANS) which has two parts -- the Sympathetic Nervous System (SNS), commonly known as "Fight or Flight," is active when the body is stressed and using energy. The second part is the Parasympathetic Nervous System (PNS), sometimes known as "Rest and Digest." It is responsible for homeostasis, which promotes repair and recovery of the body.
By measuring HRV while you sleep, you can get an objective measure of its quality by determining how much sleep time is in a SNS dominant state (and still using up energy) and how much of your sleep is in a PNS dominant state, and recharging the body's resources. HRV is also a predictive indicator of overall health and other cardiovascular events. Low HRV is associated with the development of coronary heart disease. Conversely, high HRV in the elderly population is a predictive marker of longevity.
The best solution is to ensure you get the recommended amount of sleep every night, but our modern lives do not always allow for the optimal hours of sleep. In fact, studies show more than a third of American adults don't get enough sleep. That's why it is important to make sure that when we can't get the ideal quantity of sleep, we maximize its quality.
A great way of assessing HRV while you sleep, and in your day-to-day life, is having a Lifestyle Assessment. Lifestyle Assessment combines HRV data with an activity journal over a period of 3 to 5 days and a review by a health professional who will determine what activities help your body recover or cause your body stress. It can help you find the right balance of stress and recovery to ensure that you are able to maintain a healthy lifestyle and perform to the peak of your abilities.
At Live Well Assessments we provide our clients with biometric data to help them understand how their day to day lifestyle choices are impacting upon their body in order to help them make healthy decisions to maximize their health and wellness, and improve the quality of their sleep.