Research has shown that HRV is a reliable and non-invasive marker of sleep quality and duration. HRV, or heart rate variability, measures the variation in the time intervals between consecutive heartbeats, which reflects the activity of the Autonomic Nervous System (ANS) during sleep. The ANS regulates many of the body’s automatic processes, including heart rate, respiration, and digestion, and is responsible for maintaining the body’s internal balance or homeostasis.
During sleep, the ANS shifts from sympathetic dominance (fight-or-flight response) to parasympathetic dominance (rest-and-digest response), which helps the body to relax and prepare for a restful and restorative sleep. The parasympathetic nervous system (PNS) is responsible for slowing down the heart rate, lowering blood pressure and reducing the overall sympathetic activity. This shift in ANS activity is reflected in your HRV, with higher HRV indicating greater PNS activity and better sleep quality.
Additionally, when your body taps into this rest-and-digest state, stress hormones, such as cortisol and adrenaline decrease and calming hormones including oxytocin increase.
HRV and sleep
Studies have shown that higher HRV during sleep is associated with deeper and more restorative sleep, longer sleep duration, and less sleep disturbances. In contrast, lower HRV during sleep has been linked to poorer sleep quality, more frequent awakenings during the night, and an increased risk of sleep disorders, such as sleep apnea and insomnia.
HRV and sleep interventions
HRV can also be used to evaluate the effectiveness of sleep interventions. For example, cognitive-behavioral therapy for insomnia (CBT-I) has been shown to increase HRV during sleep, indicating improved sleep quality and duration. However, according to one study, more research is needed to define “whether insomnia treatment might play a role in physiological changes associated with cardiovascular anomalies.”
Similarly, relaxation techniques such as deep breathing and meditation have been found to increase HRV during sleep, suggesting that they may be effective interventions for improving sleep quality.
In summary, HRV is a useful tool for assessing sleep quality and duration, and can provide valuable insights into the activity of the ANS during sleep. By monitoring HRV during sleep, you can identify potential sleep disturbances and take steps to improve your sleep hygiene and overall sleep quality. Additionally, healthcare professionals can use HRV to diagnose and treat sleep disorders, and to evaluate the effectiveness of sleep interventions.