Garmin's Rem Sleep Calculation: Understanding The Science Behind It

Sleep is an essential bodily function, and consistent sleep deprivation can have serious health consequences. Garmin smartwatches feature advanced sleep tracking, which offers users a full report on their sleep, including sleep/wake cycles and stages such as light, deep, and REM sleep. While there is no consensus on how much REM sleep is needed, it is important for dreaming, and this stage tends to increase in duration compared to non-REM (NREM) sleep as sleep progresses. The accuracy of Garmin's sleep tracking has been questioned by some users, who suggest that Fitbit and Apple Watch may offer more reliable data.

Garmin's accuracy in REM sleep tracking

Many Garmin smartwatches feature advanced sleep tracking, which offers a full report on sleep/wake cycles and stages such as light, deep, and REM sleep. The user is also assigned a sleep score of 0-100 with accompanying insight into the factors that influenced their score.

However, the accuracy of Garmin's sleep tracking has been called into question by some users. On Reddit, some users have pointed out that their REM sleep readings are much lower on their Garmin devices compared to other devices like the Apple Watch and Fitbit. One user even claimed that their REM sleep reading was zero minutes for one night. Another user attributed the discrepancy to the fact that Garmin uses a "weird HRV-based REM tracking algorithm" that is influenced by several factors such as training, sickness, stress, and food.

Despite these concerns, Garmin's sleep tracking technology can still provide valuable insights into a user's sleep patterns and help them identify any potential issues. Additionally, Garmin's sleep tracking feature allows users to monitor their sleep habits over time, which can be a game-changer for those looking to improve their sleep quality.

It's important to note that sleep tracking technology is constantly evolving, and the accuracy of these devices may vary depending on various factors. While these devices can provide useful insights, they should not be solely relied upon for medical advice or diagnosis. If users have concerns about their sleep, they should consult a healthcare professional for personalized advice and guidance.

REM sleep and age

Sleep is an essential bodily function directly related to both mental and physical health. While a single night of bad rest may not have a significant impact, consistent sleep deprivation can lead to heart disease, stroke, poor mental health, high blood pressure, Type 2 diabetes, and even early death.

Garmin smartwatches feature advanced sleep tracking, which offers a full report on sleep/wake cycles and stages such as light, deep, and REM sleep. This data can provide valuable insights into an individual's sleep habits and overall health.

Now, let's delve into the topic of REM sleep and age:

As we age, the quality and quantity of our sleep undergo significant changes. These alterations in sleep patterns are independent of other factors such as medical conditions or medications. Here are some key aspects of how REM sleep is affected by age:

• Decreased REM Sleep: Research indicates that the percentage of REM sleep tends to decrease as we get older. This decline is relatively small, approximately 0.6% per decade, until around the mid-70s. After that, a slight increase in REM sleep may occur.
• Age-Related Changes in Sleep Architecture: With advancing age, the proportion of non-REM sleep (stages 1 and 2) increases, while the percentage of REM sleep decreases. This shift in sleep architecture becomes less prominent among healthy older adults aged 60 and above.
• Gender Differences: Some studies suggest that men may experience a more pronounced decline in deep sleep (slow-wave sleep) with age compared to women. However, women tend to have a greater percentage of stage 1 sleep and a lower percentage of stage 2 sleep than men as they age.
• Stabilization After Age 60: Most age-related changes in sleep, including REM sleep, tend to stabilize or plateau after the age of 60. Healthy older adults generally experience less significant fluctuations in REM sleep compared to younger age groups.
• Circadian Rhythm Changes: The circadian system, which regulates sleep-wake cycles, becomes less robust with age. Older adults often experience an advance in their sleep schedule, tending to feel sleepy earlier in the evening and waking up earlier than desired. This phase advance is also observed in other circadian rhythms, such as body temperature and hormone secretion.
• Sleep Homeostasis: Sleep homeostasis, which regulates sleep pressure, declines with age. This reduction contributes to an increased number of nocturnal awakenings and a decreased ability to fall back asleep quickly.
• Neuroendocrine Changes: Age-related changes in hormone secretion, including growth hormone, cortisol, melatonin, and sex steroids, can influence sleep quality and architecture. For example, the decline in growth hormone secretion may contribute to the reduction in slow-wave sleep observed with aging.
• Daytime Napping: The frequency of daytime napping tends to increase with age. Older adults may nap more frequently due to biological changes, lifestyle adjustments, and increased opportunities during the day. However, excessive daytime napping can be associated with adverse health outcomes.
• Self-Reported Sleep Quality: Interestingly, older adults may be less likely to report sleep problems or perceive their sleep quality differently. They may accept certain sleep changes as a normal part of aging and adjust their expectations accordingly.

REM sleep and biological sex

Garmin's sleep tracking feature provides users with a full report of how well they slept, including sleep/wake cycles and stages such as light, deep, and REM sleep. The data collected by Garmin smartwatches shows that women need more sleep than men. On average, women spend 7 hours and 50 minutes sleeping each night as opposed to the 7 hours and 29 minutes men get. This is supported by SleepFoundation.org, which cites a number of reasons for this, including a woman's increased chances of having conditions like insomnia, anxiety, and depression, as well as fluctuating hormones caused by menstrual cycles, pregnancy, or menopause.

The data also shows that the older a person is, the less time they spend in REM sleep. Older people spend more time in the light sleep stage and are likely to spend larger amounts of time awake each night. Interestingly, people younger than 20 are most likely to spend 0-15 minutes awake each night, but as you grow older, your chances of lying awake begin to increase.

Garmin's sleep tracking feature is not the most accurate, and there are other smartwatches that are better at tracking sleep. However, the ability to monitor your own sleep habits over time can still be useful, and it's also good to know where you fit in with your peers.

REM sleep and stress

Sleep and stress are related to each other in a bidirectional way. Poor sleep exacerbates stress-related responses, while acute stress induces sleep rebound, likely as a way to cope with adverse stimuli. Chronic stress, on the other hand, impairs sleep and is considered one of the triggering factors of emotional-related sleep disorders, such as insomnia, depression, and anxiety disorders.

Prolonged exposure to stress without relaxation can result in shorter sleep duration and poorer quality sleep. When stressed, the body releases cortisol and other stress hormones, creating a burst of energy that prepares the body to fight or flee from danger. This hormonal cascade can lead to decreased REM sleep, resulting in impaired memory and poorer mood regulation. The lack of restorative sleep, in turn, leads to more stress, creating a cycle.

Garmin smartwatches can help monitor sleep habits and stress levels, providing insights into sleep/wake cycles and stages such as light, deep, and REM sleep. The watches also assign a stress level between 0 and 100 in real time, measured primarily using a combination of heart rate and heart rate variability data. This information can help individuals manage their stress and improve their sleep habits.

Research has shown that the first and most distinct consequence of daily mild stress is an increase in REM sleep. This increase is associated with genes involved in cell death and survival, particularly in the hippocampus. REM sleep disturbances are common in mood disorders, and these findings may help understand how stress leads to such disorders and how changes in sleep may contribute.

REM sleep and Body Battery

Sleep is an essential bodily function directly related to both mental and physical health. Sleep deprivation is linked to heart disease, stroke, poor mental health, high blood pressure, Type 2 diabetes, and even early death.

Garmin smartwatches feature advanced sleep tracking, which offers a full report on sleep/wake cycles and stages such as light, deep, and REM sleep. The user is also assigned a sleep score of 0-100 with accompanying insights into the factors that influenced their score.

REM sleep is one stage of rapid eye movement sleep and is associated with dreaming. While there is no official agreement on how much REM sleep is needed, this stage is important for dreaming, and experts believe that dreaming helps individuals process their emotions. For most adults, REM sleep takes up about 25% of the total sleep, which seems to be healthy during average sleep cycles.

Garmin Body Battery is a feature designed to help users manage their energy reserves. At any given time, users can look at their wrist to see how well the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) branches of their autonomic nervous system are working together. In other words, Body Battery shows how well the body is juggling stress, recovery, sleep, and physical activity, and gives a number on a scale of 0-100 to show how much energy is left in the tank.

Sleep is the best way to recharge your Body Battery. The higher the Body Battery is in the morning, the more likely it is that the user will have sufficient energy levels throughout the day. The data shows that those who sleep for 7 or more hours a night are 50% more likely to reach a Body Battery of 80 or greater than those who don't.

Frequently asked questions