Depending on how deeply we are asleep when the alarm clock rings, it is easier or more difficult for us to get up. An analysis by the sleep phase alarm clock helps to find out when the ideal time to wake up would be. We have summarized what it is and how it works.

In contrast to an ordinary alarm clock, the sleep phase alarm clock is designed to recognize the perfect time to wake us up. This is made possible by a permanent analysis of our movements during sleep – and thus the different sleep phases. They provide information about how deeply we are asleep. Because the fact is: In a light sleep phase, it is much more pleasant to be woken up and start the day rested than in a deep sleep phase. You probably know it too: if you are suddenly awakened from sleep, you feel weak and sluggish. This feeling usually lasts throughout the day. A sleep phase alarm clock can be very useful to make getting up easier. But how exactly does it actually work and how do the common models differ? An attempt at an explanation.

How does a sleep phase alarm clock work?

Before we get into how it works, you need to know that there are two different types of sleep phase alarm clocks: those that can record brain activity – and those that measure (physical) movements. The first variant is not intended for private use, but is used in professional sleep laboratories. The second variant, on the other hand, is suitable for at home and is therefore decisive for the following summary.

Basically, a distinction is made between four different sleep phases:

As the name suggests, the phases relate on the one hand to the duration and on the other hand to the intensity of sleep: In the light sleep and REM phases (REM stands for Rapid Eye Movement and translated means something like “rapid eye movement”) we dream a lot and move accordingly more. If we are woken up in one of these phases, for example because the alarm clock rings, it is usually very easy to get up. In the deep sleep phase, on the other hand, our body recovers from the day before, so that we move less – and sleep particularly soundly. As a result, we automatically feel drained and drained when we are suddenly woken up. And that’s exactly why there is the sleep phase alarm clock. He should be able to recognize the light and deep sleep phases of a person in order to wake him up more gently. This is made possible by recognizing the increased movements during light sleep and REM phases.

Analysis: How to evaluate your sleep

We usually set an alarm clock to wake us up exactly when we want to get up. Which can inevitably lead to us being torn out of a deep sleep phase. With the sleep phase alarm clock, on the other hand, it is not a time that is set, but a period of time – as soon as you know your morning almost-wake phases. In order to determine this, the device must be fed with data. The technology required for the analysis can be found in the following models, for example:

This is a so-called sleep sensor from Beurer, which you can use for professional sleep analysis: The SleepExpert only has to be pushed under your mattress to measure and evaluate your movements during sleep. According to the manufacturer, the device is able to distinguish between light and deep, awake and REM sleep phases. This means that the model can also be used as a sleep phase alarm clock. With the help of the collected data and the integrated fresh wake function, you will be woken up gently every morning at the right time.

Most digital wristwatches are now able to measure your movements while you sleep: the Apple Watch Series 3, for example, can use the “Sleep Cycle” app to record and analyze your sleep phases. You then have the opportunity to evaluate the data and adapt it to your inner rhythm. In other words, you set the alarm on your watch so that it always wakes you up when you are in a light or REM sleep phase. Alternatively, you can also use a fitness tracker, such as from Fitbit.

This is also a type of sensor that is placed under the mattress and analyzes your sleep cycle (i.e. heart rate, breathing cycles and movements). According to the manufacturer, the Withings Aura Sleep System can use the collected data to gently wake you up when you are in a light sleep phase. In addition to the intelligent “Smart WakeUP” alarm function, the device also includes a light alarm clock: The dimmable LED light is said to have a positive effect on your sleep-wake cycle by using certain light waves that produce melatonin (the sleep hormone that makes you sleepy). can contribute.

Note: The article was first published in April 2021.

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