Understanding Deep Sleep And Rem With Apple Watch

The Apple Watch allows users to track their sleep patterns, including the time spent in each sleep stage: REM, Core, and Deep sleep. However, the term Core sleep has caused some confusion as it has different meanings in the scientific literature and Apple's definition. In the Apple Watch, Core sleep is equivalent to light sleep, which includes the Non-REM stages 1 and 2, while Deep sleep refers to the harder phase of the sleep cycle, and REM sleep occurs at intervals during the late part of the night.

Core sleep is light sleep, which takes place in the first few hours of sleep

Core sleep, as defined by Apple, is the same as light sleep. This is the stage of sleep that occurs in the first few hours of sleep. It is also known as N2 sleep, and it usually makes up about half of your sleep time.

The Apple Watch categorises sleep into four different states: light ("core") sleep, deep sleep, REM sleep, and being awake. Light sleep is defined by Apple as the first two stages of non-REM sleep, or N1 and N2. N1 only lasts a few minutes, during which your body begins to relax and your brain waves start to change. N2, which makes up most of what Apple calls core sleep, includes spikes of brain activity called sleep spindles and distinctive brain wave patterns called K-complexes. This is the stage during which we consolidate our memories, and it is also when people tend to grind their teeth.

Sleep scientists give the following approximate breakdown of the stages of sleep:

• N1 (very light sleep): About 5% of the total (just a few minutes)
• N2 (light or "core" sleep): About 45%, so just under four hours if you normally sleep for eight hours
• N3 (deep sleep): About 25%, so about two hours if you normally sleep for eight hours
• REM: About 25%, so about two hours

It is important to note that the term "core sleep" has been used in scientific literature to mean a few different things, and it is not a recognised sleep stage. Apple chose to rename the sleep stages its watch can detect, and so its definition of core sleep does not align with common uses of the term.

Additionally, while wearables like the Apple Watch can be useful for understanding your sleep patterns, they are not always accurate in determining the specific sleep stage you are in.

Deep sleep is harder to wake someone up from

Deep sleep, the third stage of non-REM sleep, is harder to wake someone up from. This stage is often referred to as "slow-wave sleep" and accounts for about a quarter of a person's sleep each night. During this stage, the body undergoes the most repair, including muscle recovery, bone growth, and strengthening of the immune system. As people age, they spend less time in deep sleep and more time in the lighter stages of sleep.

The Apple Watch can estimate the time spent in each sleep stage, including deep sleep, by tracking movement and heart rate. However, it is important to note that wearables like the Apple Watch may not always accurately distinguish between the different stages of sleep. The Apple Watch categorises non-REM stages 1 and 2 as "core sleep" or light sleep, and stage 3 as "deep sleep". According to sleep data from Apple Watch users, the average amount of deep sleep per night is 50 minutes, with 71 minutes being in the top 10% and 28 minutes in the bottom 10%.

To improve deep sleep, it is recommended to maintain a cool, dark, and quiet bedroom environment. Additionally, avoiding alcohol and caffeine in the evenings and incorporating a bedtime routine that includes at least 30 minutes of winding down can be beneficial. While the Apple Watch can provide insights into sleep patterns, it is important to interpret the data with caution and consider other factors that may impact sleep quality.

REM sleep is optional sleep, which occurs at intervals during the late part of the night

Sleep is divided into several stages, and the Apple Watch can help you track the time spent in each stage. According to Apple, "Core sleep" refers to light sleep, which includes the Non-REM stages 1 and 2 (N1 and N2). "Deep sleep" is the phase where it is harder to wake someone up, and it is considered the most important sleep stage for physical repair and immune function. Finally, REM (Rapid Eye Movement) sleep occurs at intervals during the late part of the night and is considered optional and less crucial.

REM sleep is often associated with dreaming and rapid eye movements, as the name suggests. While it is considered optional, it still plays a role in our overall sleep architecture. Typically, we cycle through the different sleep stages throughout the night, and REM sleep tends to get longer with each cycle. So, while you may not remember your dreams or be aware of your eye movements, REM sleep is indeed occurring and is a normal part of your sleep cycle.

It is worth noting that the Apple Watch's sleep tracking primarily relies on movement to detect sleep stages, which may not always be accurate. However, it can still provide valuable insights into your sleep patterns. The watch estimates the time spent in each sleep stage, including REM, and this information can be viewed through the Sleep app.

While REM sleep may be considered optional, it still has its purpose. During this stage, your body is temporarily paralyzed, except for your eyes and breathing muscles. This stage is also associated with dreaming and memory consolidation. Additionally, as you cycle through the sleep stages, REM sleep usually becomes longer with each cycle, indicating its increasing importance as the night progresses.

Overall, while you may not consciously control whether you enter REM sleep, it is a natural and essential part of your sleep cycle that occurs at intervals during the latter part of your night's rest.

Sleep tracking on the Apple Watch uses motion to detect sleep

The Apple Watch's sleep tracking feature uses motion and heart rate data to determine when you are asleep and in different stages of sleep. It can detect when you are in light sleep, deep sleep, or REM sleep. However, it is important to note that the Apple Watch is not as accurate as a sleep study with more sophisticated equipment, such as an electroencephalogram (EEG). The watch is limited to the data it can collect through motion and heart rate sensors.

Despite the limitations, the Apple Watch is considered one of the most accurate sleep trackers among smart wearables. It can provide valuable insights into your sleep patterns and help you understand your sleep quality. The watch can also be used in conjunction with other health and fitness features of the Apple ecosystem, such as the Health app, to get a more comprehensive overview of your health and well-being.

To use the sleep tracking feature on the Apple Watch, you need to wear it to bed. The watch will then track your sleep and provide you with information about the duration and quality of your sleep. You can also set up sleep schedules, sleep goals, and wind-down times to help improve your sleep habits.

It is recommended to have a consistent wake-up time and a bedtime routine that includes at least 30 minutes of winding down with relaxing activities. Avoiding screens, alcohol, and caffeine before bed can also improve your sleep quality. By making these changes and utilizing the tools provided by the Apple Watch, you can work towards achieving better sleep and improving your overall health.

The Apple Watch can also track your breathing rate as you sleep

The Apple Watch can track your breathing rate as you sleep, providing greater insight into your overall health. This is done through the Health app on your iPhone. After wearing your watch to bed, you can access your respiratory rate data by going to "Browse" and then "Respiratory". From there, tap "Respiratory Rate" and then "Show More Respiratory Rate Data". The Sleep entry will show the range of your respiratory rate as you slept. It's important to note that these respiratory rate measurements are not intended for medical use. If you wish to turn off respiratory rate measurements, you can do so in the Settings app on your Apple Watch or through the Apple Watch app on your iPhone.

In addition to tracking your breathing rate, the Apple Watch can also monitor your sleep. The Sleep app on the Apple Watch allows you to create sleep schedules to help you meet your sleep goals. By wearing your watch to bed, the Apple Watch can estimate the time spent in each sleep stage: REM, Core, and Deep. It can also track when you wake up. When you wake up, you can open the Sleep app to see how much sleep you got and review your sleep trends over the past 14 days.

It's worth noting that the Apple Watch's sleep tracking feature uses your motion to detect sleep stages. While it provides valuable insights, it is not as accurate as a sleep study with more sophisticated equipment such as an electroencephalogram (EEG). Nevertheless, the Apple Watch can be a useful tool for understanding your sleep patterns and making informed decisions about your sleep habits.

According to sleep data from Apple Watch users, the average Apple Watch user gets 50 minutes of deep sleep, 87 minutes of REM sleep, and 267 minutes of core sleep per night. This data can be used to compare your own sleep patterns and see how you measure up. However, it's important to remember that individual sleep needs may vary, and it's always a good idea to consult with a healthcare professional if you have concerns about your sleep.

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