11 October 2019

Change or Reset your Circadian Rhythm on CPAP

“Many people will walk in and out of your life, but only true friends will leave footprints in your heart.”
- Eleanor Roosevelt (Former First Lady of the United States – 1884 – 1962)

One day it occurred to me that I could change or reset your circadian rhythm on CPAP. You can change the circadian rhythm on a particular night by using a CPAP and Bilevel or BiPAP machine with different settings. When I use a Bilevel auto adjusting machine with different settings, I have a different circadian rhythm or sleep cycle for each different setting. By using the Bilevel machine I have optimized my sleep every day.

By understanding that your circadian rhythm is your friend, you can optimize your sleep each day. Circadian rhythms are your body's internal clock or sleep/wake cycle which repeats roughly every 24 hours. Ideally, wake up at the end of a sleep cycle not in the middle of one otherwise you may feel tired and sleepy all day.
For some time, I could not understand why I was waking up at different times in the morning. Generally, the wake times can vary by up to 75 minutes. I thought everyone only had one circadian rhythm such as 90 minute sleep cycles during the night. In addition, I thought it was sleep apneas that were occurring that was waking me up at different times in the morning.

In a previous blog post, Use Different CPAP and Bilevel Settings, it was mentioned that I use 3 ResMed VPAP Auto adjusting bilevel machines with different settings on each to optimize my sleep every day. The machine I use each day is dependent on the situation that I am facing each day. The situations could be eating and drinking late, a hard day at work or doing a lot of physical activity and a normal day. 

The average sleep cycle length is as follows: 
Machine 1     Normal day                  75 - 80 minutes
Machine 2     Hard day at work/        80 - 83 minutes
                     Heavy physical day    
Machine 3     Eat/ Drink late              90 - 93 minutes 

Usually with Machines 1 and 2, I will sleep for 5 cycles or between 6 hours 15 minutes (375 minutes) to 6 hours 55 minutes (415 minutes) before waking up.

Machine 3, Eat/ Drink late usually results in either 4 or 5 cycles or 6 hours (360 minutes) or 7.5 hours (450 minutes) before waking up. 

Whichever machine is used, once I wake up, I will sleep/ doze until I reach 7 hours and 30 minutes to 8 hours. That is, I will go another sleep cycle if necessary, so I have consistency when I sleep and wake up. You can see with machine 3 that I may not wake for 7 hours 45 minutes (5 cycles x 93 minutes). Using Machine 1, sleeping 5 sleep cycles may be only 6 hours 15 minutes (5 x 75 minutes). 

In addition, I found the extra time from waking up at the end of the last cycle up to 8 hours of sleep and rest gives me that bit extra of up to 10% of wakefulness during the day. I no longer have a late afternoon/ early evening “little tired” period and falling asleep. The extra sleep time keeps me going strong till bed time of 11.30pm to 12.00pm. 

By working out what my body naturally requires, I have stopped using the alarm clock to wake up. Now I only use an alarm clock in emergencies as a backup when it is essential I get out of bed by a certain time. 

These sleep cycles will vary for each person. You can read more about 90 minute sleep cycles and the splitting up of sleep into two sleep sessions.  


Circadian rhythms are critical should I not be able to get 7 hours 30 minutes to 8 hours sleep/ rest. For example, when you need to get on a plane and have an urgent event to attend. I had to attend a funeral on Friday and get a plane. I had only 3-4 hours available to sleep. By working out the circadian rhythm for each machine, as I was on Machine 3 and had eaten and drunk late on Thursday, I knew the cycle would be normally 90 minutes. So, I had 2 cycles or 3.0 hours of sleep. 

I was on my feet nearly all day and did not arrive back home and go to sleep till 2.37am, Saturday morning some 23 hours later from when I first woke up. I was generally feeling great all day. Had a little tiredness in the afternoon but I kept going and was feeling fine. 

Saturday morning, I used Machine 2 and woke 8 hours 23 mins later. This is 6 cycles x 83 mins or 503 minutes. As it was the end of the cycle I got out of bed. I had to go to a meeting and function and did not get to Bed that night or Sunday morning to 2.51am. Again, I felt pretty good all day. 

As I had eaten late on Saturday night, I used Machine 3 and slept to 10.19am or 7 hours 28 mins later. This is 5 cycles x 90 mins or 448 minutes. 

This is an example of how I use the circadian rhythm cycles to my advantage. It is essential that you work out your own personal cycle as they will differ for each person. So when you find yourself in a similar situation you can work out when it is optimal for you to wake up and get out of bed. The alarm clock is set as a backup only. From personal experience, should I wake up in the middle of a sleep cycle, I will be tired and sleepy for the rest of the day. By using cycles, you can be refreshed and energized all day even though you have not had your normal amount of sleep. 

Interesting, using the plane example, after 3.0 hours when I needed to get up out of bed, I awoke automatically and did not need to use the alarm clock. It was as if my body knew I needed to get up! 

If I was using Machine 1, normal day and 75 minute cycles instead of Machine 3, eat/ drink late and had 3.0 hours of sleep, you can see I would have woken up in the middle of a sleep cycle. 2 cycles x 75 mins = 150 mins or 2 hrs 30 mins. 3 cycles x 75 mins = 225 mins or 3 hours 45 minutes. 

You will note that I have average cycle length for each machine and I do not have a precise circadian rhythm like other people such as 90 minute cycles. There are a few reasons. 

1. Sometimes there is a crossover in what I am doing for a particular day. For example, I may have a Normal Day with a lot of walking and a very large lunch. Using Machine 1, the cycle length will normally be 80 minutes rather than 75 minutes as shown above. That is, the cycle length will move towards the cycle lengths of Machines 2 and 3. Read more at: Different Bilevel Settings Example.  

2. Using different machines may cause the first day of switching to have a slightly different sleep cycle. By the next night and thereafter should I stay on the same machine, the sleep cycle stabilizes and the length of the cycles are the same. 

3. In addition to sleep apnea, I have a genetic disorder, Hemochromatosis. This disorder is characterized by having too much iron absorption from the foods that you eat. Where your iron levels are too high, you may feel incredibly tired and lethargic and may lead to health issues such as cirrhosis of the liver, heart disease and diabetes. As an aside, when my iron levels are too high, my skin colour starts having an orange tinge to it. 

Body iron level helps regulate our circadian rhythms and their link to metabolism. You can read more at this article.


Importantly, Hemochromatosis is a medical condition associated with Alzheimer's Dementia. More details are on the blog post: 

In additon, Research is supporting that a brain's ability to clear a protein closely linked to Alzheimer's disease is tied to our circadian cycle.

Rensselaer Polytechnic Institute. "Clearance of protein linked to Alzheimer's controlled by circadian cycle: Ability of immune system to destroy Alzheimer's-related protein oscillates with daily circadian rhythm." ScienceDaily. 10 February 2022.


To have great sleep every day, I use different settings on the sleep apnea machine. These settings depend on the situation that I am facing for a particular day. Using different settings changes my circadian rhythm. By using circadian rhythms as my friend and to my advantage, I can optimize my sleep every day.
Should you be having side effects and issues with your sleep apnea therapy; CHANGE what you are doing so that you can wake up feeling refreshed and energized each day.

“Have courage. Be adventurous and Go for it! Overcome your fear.”
- Mrhelpful

No comments:

Post a Comment