Sleeping Cycle

A single sleep cycle consists of 5 stages. These stages repeat every sleep cycles. The duration of one sleep cycles is between 90 and 120 minutes. And this duration remains constant. The five stages are:

- Stage 1: Brain activity high. You can be awakened easily. So, this is the best moment to wake someone. You will be feel energetic then.

- Stage 2: Stage 1 and 2 are together light sleep, which is a half of the total sleep; eye movements stops and brain activity will be lower.

- Stage 3/4: Brain activity will be low. Stage 3 and 4 are together deep sleep, which is a quart of the total sleep; brain activity is very low. It is difficult to wake someone in this stages. And if a person is waking up in this stages, he will be disorientated. So this stage isn’t a good moment to wake someone. There is no eye movement or muscle activity. In this phase most ‘accidents’ happen, like bedwetting and sleepwalking. But in this phase there will be a lot of recover processes in your body. So this is the most important part of your sleep.

- REM-sleep: A quart of the total sleep; brain activity high. Muscle strain very low, but little eye movements under eyelids. Information and emotions will be processed. In this phase dreams occur, and, if awoken during REM-sleep, a person can remember this dreams. This phase will always be at the end of the sleep cycle. This phase isn’t a good moment to wake someone.

The sleep pattern will change with age. So we’ve to pay attention to someone’s age.[3] The duration of the REM-sleep will decrease with the age.[6] People from 20 years old will have 2 hours REM-sleep over the night, and people from 70 years old will have 45 minutes REM-sleep over de night. So, it can be concluded that older people have to sleep shorter to get the same recovery, because they sleep more efficient.

The first three sleep cycles are the most important. In the first three sleep cycles, you’ll get the most deep sleep. This is less in the last sleep cycles. So you’ve to sleep AT LEAST 5 hours.[4]

Snoozing hasn’t any purpose. When you are snoozing, you won’t get in a deep sleep, so you won’t be more recovered after snoozing, that you was before you start snoozing. So the Smart bedroom don’t need a Snooze function. [5]

What is the best moment to wake someone (combination of sources)

As said before, you’ve to be in a deep sleep to recover your body. [1] The deep sleep is quite at the end of a sleep cycle. The last part of every sleep cycle, the REM-sleep, is not a good moment to wake someone. You will be disorientated and you’ll feel yourself sleepy. So the best moment to wake someone is after the deep-sleep and REM-sleep. This is after a complete sleep cycle. The best wake-up moment is at the beginning of a new sleep cycle, the light sleep phase. The Smart Bedroom have to look what’s the best time to wake someone, with this information in his mind. [8] For example, the Smart Bedroom observed that a person has complete a sleep cycle, that person will then start a new sleep cycle. If the Smart Bedroom calculated that the person cannot finish a complete sleep cycle until the person will reach stage 1 and 2 again, before his alarm will go, he could better wake that person immediately after finishing the previous sleep cycle. (when you’re in the light sleep)

References

Sources:

[1] Sleepdex, stages of sleep, http://www.sleepdex.org/stages.htm

[2] I. Feinberg, T. C. Floyd, Systematic Trends Across the Night in Human Sleep Cycles, jan 2007, http://www.readcube.com/articles/10.1111%2Fj.1469-8986.1979.tb02991.x?r3_referer=wol&tracking_action=preview_click&show_checkout=1&purchase_referrer=onlinelibrary.wiley.com&purchase_site_license=LICENSE_DENIED_NO_CUSTOMER

[3] I. Feinberg, Changes in sleep cycle patterns with age, October 1974, http://www.sciencedirect.com/science/article/pii/0022395674900119

[4] Inslaap.nl, De slaapcyclus: werking van de slaapcyclus, juni 2015, http://www.inslaap.nl/begrijpend-slapen/slaapcyclus-werking-slaapcyclus/

[5] Inslaap.nl, Stoppen met Snoozen (en win tijd!), jun 2015, http://www.inslaap.nl/beter-slapen/stoppen-met-snoozen/

[6] D Purves, G.J. Augustine, D. Fitzpatrick, M.A. Sunderland, Neuroscience (2001), 2nd edition, http://www.ncbi.nlm.nih.gov/books/NBK10996/ (The information at this site is coming from this book)

[7] Azumio, Sleep Time (app), http://support.azumio.com/customer/en/portal/topics/667008-sleep-time/articles

[8] Azumio Inc., wake up during your lightest sleep, (February 2015), https://www.azumio.com/blog/health/sleep-cycle-why-you-should-wake-up-during-your-lightest-sleep