Circadian Rhythms & Temperature

Due to a bit of an erratic week, I haven't been able to reliably measure (and experiment with) my apnoeas, so instead this was going to be a blog post about "Circadian Rhythms" (the daily sleep/wake cycle).

Given that we inhabit a planet with a 24 hour day, it is no surprise that our bodies have become roughly linked with the day/night cycle, with various hormones being released at certain stages in the rhythm enticing us to sleep or wake.  

               (Combined photos from my Sky-Watcher and solar telescopes)        

Not everyone's rhythm is the same, some people have theirs shifted (such as when you are jet lagged). Even a skew of an hour or two can make a huge difference to how easily you are able to wake up for work in the morning, or how late you can stay awake.

There are a couple of online questionnaires to help you determine your own circadian rhythm:

http://www.philips.co.uk/c/circadian/178344/cat/
http://www.bbc.co.uk/science/humanbody/sleep/crt/

Both of these decided that my rhythm was skewed, so I decided to make my own measurements and chart them here but after seeing the first 24 hours of data, something interesting emerged...

This is a normal circadian rhythm taken from the Philips website. 

In fact, this is a simplified rhythm, because it is normal to have a small dip in the energy levels around mid afternoon, hence the reason for many countries having an afternoon siesta, and the reason why we tend to slump at our desks in the mid afternoon and reach for a cup of coffee.

This dip can be seen in my graph from the BBC circadian test.

Core body temperature is a good way of charting your own rhythm because energy levels are reflected by our temperature. Our body temperature is not a static 37.5 C, in fact it fluctuates throughout the day inline with our circadian rhythm. Of course, it is also affected by ambient temperature and how active we are.

So, all it would take to chart my own rhythm would be a decent thermometer.

I decided to get a data-logging thermometer, so that I could see what was happening while I was asleep.

I ordered a thermometer capable of recording every 10 seconds (to weed out anomalous readings), and was expecting the probe to be a small thermocouple-type sensor that I could stick to the skin under my arm, but the probe was more like a bullet and wasn't adhesive plus the logger turned out to be a lot bigger than it looked in the photo!

I'd gone this far, so in the name of science, I shaved under my arm and fixed the probe there with Melonin (low adhesive dressing) and Tegaderm (a clear waterproof adhesive dressing). I then wedged the cables into my suit and went off to work.

After 24 hours (and a few weird looks) I downloaded the data to a computer. I noticed that generally the pattern was the same as that belonging to "normal" people, but that it had a few fairly severe drops in temp during the night.

I repeated this over several days.

On the graph below, the dip is around 1:30pm and again at 4:00pm. I suspect the 1:30pm dip is my normal afternoon energy dip whilst the 4:00pm dip is environmental because I was working outside at 4:00pm. 

I repeated this the following day and the dip was much more pronounced again early at around noon, but I ended the recording early as it was becoming awkward to carry the data-logger around with me, so I can't show a full 48 hour graph.

It's also interesting that the temperature drops around 8pm. That's pretty much when I start to look forward to sleep! It plateaus at 10pm for a couple of hours in a similar way to the one produced by my answers to the BBC link. This may have been because I was already asleep by then!

The first 24 hours...

Those drops in temperature during sleep are severe. When I first saw them, I suspected that they were erroneous readings, but the probe was stuck so tightly to me that there was no way that these were due to poor contact (after all, if that were the case, why didn't this happen during the day when there was more movement?). However, as the data rate on the logger was so high (240 recordings an hour), these were clearly not erroneous as they slowly crept back up to the plateau level of around 36.5°C.

I wasn't happy with this result, so I repeated it the following night. The drops in temperature were still there.

On the second night, to eliminate the possibility that these variations were due to environmental changes, my room temperature was monitored with another probe, and it was a surprisingly constant 18°C  for most of the night, so there were no corresponding dips in room temperature. I don't like my bedroom to be too warm so I switch the heating off at night.

I took a look at my sleep-stage data using the Zeo, and was surprised that the seemingly random falls in temperature coincided with awakenings from REM! (Shown as orange "wake periods" on the coloured graph, but as REM/Wake on the detailed graph. Light green = REM, Dark green = slow wave sleep, grey - stage 1 & 2 sleep. For the sake of simplicity I won't show the detailed graph, but you can see one on the blog post "My Baseline AHI").

So what's going on?

Along with the muscle paralysis that comes with REM sleep (to stop us acting out our dreams), there is also a decrease in the body's ability to regulate its temperature (thermoregulation). 

So, it seems that my temperature was dropping, causing me to wake in order to regulate my temperature, pretty much in the same way that my apnoeas cause me to wake during REM.

If this is true then it means that in order to be able to stay asleep during REM I now have two issues to deal with: apnoeas AND temperature!

During REM this decrease in ability to regulate our temperature causes us to be largely "Poikilothermic" (meaning that our temperature is governed by the temperature of our environment). So the key to eliminating this issue is to regulate the temperature of my bedroom better.

I repeated this for two more days, and then concentrated on the nights and gathered more data (total of 5 nights). It seems that these overnight drops in temperature aren't always correlated with REM sleep (sometimes they are just before and sometimes just after), so until my more accurate thermometer arrives, I decided to calculate the mean temperature from the week's recordings to get a better idea of my rhythm and to try to eliminate the overnight drops.

This gives a much nicer picture and goes some way to reducing the environmental effects. The data fits well with how I feel throughout the day. I tend to get a bit tired at 1pm, then start considering bed around 8-9pm.

Compared to the BBC graph, it lines up fairly well, although my "energy drop" happens earlier in the day at a more accurate time.

I'm not comfortable with this experiment as there is much that could be improved on:  

• Better temperature sensor (on it's way)
• Eliminate environmental temperature effects (maybe on a day where I stay at home)
• I still am not convinced whether these changes in temperature are an effect of activity. After all, it stands to reason that when we are more active our bodies produce more heat, so it would be interesting to do this on a day where I forced myself to do nothing, stayed at home and forced myself to stay awake past my usual bedtime, that way I could see whether these changes are still evident on the graph. That said, some of the nights were recorded with an 11pm bedtime although my temperature still dropped as usual around 8pm, so it could be accurate.

One thing that it has shown me is that it is essential to have your sleeping environment just right for you...

A good sleep routine involves making sure that your bedroom is the right temperature. It should be cool but not cold. In days gone by, the outside temperature dropping in the evening acted as a cue for our ancestors' bodies to sleep. Of course, in days where our homes are heated, this confuses the body and can lead to poor sleep.

The same is true with light. Nowadays we have artificial light filling our homes and offices, and that also interferes with our sleep/wake cycle as we don't receive the nighttime cues.

So sunlight during the day and a cool, dark bedroom goes some way to remedying this.

Update on Friday, December 9, 2011 at 8:46AM by Hypnagogia Blog

My new monitor arrived. It's able to record temperature, blood pressure, ecg trace, heart rate and oxygen saturations together.

I still saw temperature drops, and they still correlate with REM sleep.

The following screenshot (combined with the Zeo hypnogrm) shows the temperature drop along with changes in heart-rate during a REM period.

Key

Zeo hypnogram
Oxygen saturations
Pulse rate
 Temperature

5-HTP, Serotonin and Sleep

 

For the last 5 days I've been taking 5-HTP.

5-HTP is a precursor to serotonin (that is, it becomes serotonin once metabolised by the body).

I've previously used 5-HTP for experimenting with my sleep composition, and to try to reliably trigger lucid dreams. The dosage that I was taking then was 50 - 100mg at night.

This time I tried a brand that contained "co-factors". These are associated vitamins and minerals that help the body to metabolise the 5-HTP into serotonin. 

I decided on 200mg each night about 10 minutes before getting into bed. 100mg is the recommended maximum daily dose of this brand, although I have seen others that give a maximum daily dose as 300mg.

I have also seen medical literature that cites doses of 150mg-300mg as a daily dose (as a trial for treating depression), so toxicity at this dose seemed unlikely.

Why did I take 5-HTP?

The rather lazy answer is that (as I mentioned above) I've taken it before without ill effect, and that it is mentioned to have a positive effect on sleep, even being cited as having a positive effect on a severe case of insomnia 

A rather cheeky and over-simplified answer is that I have already shown that a depressant (alcohol) increases my AHI, so I wondered if something that has antidepressant properties would have the opposite effect and reduce my AHI.

I have also seen medical literature that suggests a link between depression and sleep apnoea (both as a cause and effect of sleep apnoea). 

Depression is more complicated that just having low serotonin levels, but low serotonin does play a part. Serotonin is a neurotransmitter (it is used in the body's sending and receiving of nerve impulses), so I wondered if increasing my levels would mean that I would have stronger signals to breathe during sleep and that the muscle tone in my airways would be that much "sharper".

Okay, so how did the 5 days go?

I noticed the following effects (sleep related and non-sleep related):

• I wasn't as tired in the evenings, so went to bed later
• I found it easier to wake up
• I didn't feel as hungry during the day, generally ate once at 2pm, then didn't eat in the evening.

Throughout these experiments, I go to bed when I am tired.

I calculated my average bedtime using the Zeo data. As I am doing these 5-day comparisons on weekdays (except the alcohol test - see separate blog for that), the time that I had to wake up was the same each day, hence later to bed meant less time in bed, which oddly with the 5-HTP didn't feel like a bad thing.

 

I wondered if my body "needed" more sleep, afterall I am used to roughly an extra hour (and still crave more), but on two mornings of the week (Fri and Sat) I can have a bit of a lie-in if I need to but I didn't want to lie in when taking 5-HTP at night (It's Saturday and I'm typing this at 7am, after waking up at my normal weekday time of 6:30am)!

It is known that some anti-depressants can decrease the amount of REM sleep that you have, so I suspected that my percentage of REM would decrease.

As percentages, the figures do not show this. In fact they show an increase in the percentage of deep sleep, along with a slight increase in REM and wake...

However, as REM is more abundant at the end of the night, it follows that the less time one spends in bed, the less opportunity there is for REM sleep, hence my actual 5-day-mean time in REM fell by 11 minutes from my baseline of 98 minutes, although it put it more inline to the average for my age of 90 minutes.

My actual time in slow-wave sleep (deep) rose by a mean of 3 minutes.  My mean deep sleep (34 minutes) is still way below the average for my age (69 minutes) but within limits, so I am pleased with this small increase.

I'm not sure if these changes are actually significant, perhaps a longer trial may reveal more?

So, even if 5-HTP didn't affect my AHI, it still had positive effects on several aspects of my sleep composition. 

However, it did have a positive effect on my AHI and it was much more noticeable... 

I've graphed my 5-day-mean AHI alongside the other 5-day-mean AHIs for alcohol and my baseline.

It brings my mean AHI down to a level that puts me in the "normal" category (<5 AHI = normal). Maybe this is the reason for not wanting to sleep so early and finding it easier to wake in the mornings.

For the sake of showing that this is a consistent effect, I also graphed the data on a night by night basis... 

For now, this seems too good to be true: 

• Lower AHI
• Normal bedtimes
• Less time in bed
• Increase in slow-wave sleep

So what now? Keep on taking the tablets?

Based on my limited data, I wouldn't dare go so far as to claim that this is a effective treatment for mild (very mild) obstructive sleep apnoea, nor would I suggest that it would work for others, but it is intriguing and does need looking at further.

It leaves me wanting to know more about the mechanism behind this effect. Yes, it's good that it has helped me as far as my AHI is concerned, but I want to know how. In a previous post, I noted that my sleep apnoea seems to be REM related. Serotonin related activity drops dramaticaly during REM sleep, so maybe the higher levels due to 5-HTP reduced that effect?

Is my pseudo-science hypothesis correct, or is there more to it than that?

I'd be interested to see if this effect carried on, or if my body got used to the 5-HTP and the effect faded.

I'd also like to try this with a lower dose of 5-HTP (after all, why take a high dose if you don't need to)? I'd also like to see if sustained-release 5-HTP is more effective.

I was planning to try the mandibular advancement device next, but after such a positive effect, I think I'll stay with 5-HTP for a while and see if I can improve on the results even more. I'd like to bring my sleep latency (time to sleep onset) down.

Yes, this is good news but I can't help feeling a little like Lizzy in "Drop Dead Fred", she knows that she's taking a pill that will stop her seeing things that others can't. Will taking 5-HTP, increasing my serotonin levels and bringing my AHI down stop me from having sleep paralysis, lucid dreams and seeing/hearing the sleep-wake border imagery that I have grown so used to? 

I hope not.

I'll explain how and why I came to like sleep paralysis in an upcoming blog-post. Hopefully it may be of use to anyone that fears it as I used to.

I have to say that this is a test with a tiny sample size, and of limited duration. I am not suggesting that anybody should try this, and certainly not use it in place of recognised treatments. 

Update on Saturday, May 12, 2012 at 7:54PM by Hypnagogia Blog

I've also found that 5-HTP helped reduced residual snoring after lowering my AHI with positional therapy.

Snoring Remedies? Results for 5-HTP

Apnoeas, me? My Baseline AHI

I'm going to be exploring some of the sensible and not so sensible suggestions in order to bring down my AHI (see my post "What is an Apnoea?" for an explanation).

To do that I needed reliable data, so I decided on a 5 day mean with a few basic rules:

• No coffee after 3pm
• Monday - Friday monitoring only (to ensure routine sleep and wake times)
• No alcohol
• No other supplements known to affect sleep
• Begin sleep on my back (supine)
• Motion detection IR camera (for verification of events if needed)
• The same apnoea / hypopnea scoring criteria will be used throughout

I could use the IR camera to detect sleep position, but that would take a lot more time, so until I have a system that can detect that reliably then I won't include that data, and I may re-evaluate some weeks using that ability.

I did initially check the camera to see if I attempted to breathe when the system was detecting apnoeas. I did make some respiratory effort, so I will make the presumption (for now) that my apnoeas are obstructive in nature.

I also noticed that when the oxygen desaturations due to apnoeas were compared to the Zeo hypnogram, that like my son's, they were clustered around REM sleep.  

The top line is my oxygen level.

It does look like I'm awake for those periods, but the black line is a more detailed Zeo hypnogram (data calculated on a 30 second basis). Zeo has a scoring system and shows the highest scoring sleep stage as being the dominant one. "Wake" scores the highest; this makes sense, as being awake is probably the most important thing to show when you are supposed to be sleeping.

The 30 second graph shows why the main Zeo graph shows a lot of wakefulness during the night... I have oxygen desaturations which in turn wake me up, hence Zeo shows "wakefulness for the whole 5 minute epoch. However, when you see Zeo's calculations of time spent in each sleep stage, these are based on the more detailed 30 second data.

Sleep apnoea can run in families. Whether that is a factor or not, my diagnosis (albeit a self-diagnosis) doesn't surprise me. I sometimes snore, I wake up with headache a lot, and I could do with losing a bit of weight.

I have long suffered with sleep paralysis, and I suspect that being disturbed in REM sleep is a major factor in that, if not the sole cause.

So, how is this a problem?

My average AHI (number of apnoeas and hypopneas per hour) is 7, hence I am classified as having "Mild Obstructive Sleep Apnoea".

The classification ranges are:  

<5      -    Normal (unless symptomatic)
5-15   -    Mild
15-30 -    Moderate 
30+    -    Severe 

The REM element brings the name to "Mild REM-Related Obstructive Sleep Apnoea"

I will say that this "diagnosis" is an amateur one, it may not correlate with a professional one in a sleep lab, but if I use the same equipment throughout this experiment the results will still be valid, just relative to my original numbers.

So, what if I don't want to have that diagnosis, what if I want to be "normal" (says the man who sleeps with electrodes on his head, prongs up his nose and a camera watching him)?

Standard advice:

• Lose weight if you are overweight (even a small amount can make a difference)

That's all very well, and something that I will do, but that won't help me fix my sleep tonight will it?

Other advice includes:

• Prop the head of your bed up by 4-6 of inches (takes the weight off your neck)
• Cut down on alcohol (see this blog entry on alcohol)
• Quit smoking
• Use a mandibular advancement device (pushes the bottom jaw forward to hold the airway open)
• Use a CPAP device (see this blog entry on NIV)
• Avoid caffeine and heavy meals within two hours of bed
• Use a nasal dilator (keeps the nostrils open)
• Try a nasal saline spray
• Throat exercises
• Surgery

I'll evaluate some of these (plus a few more ideas that I have) and back up the findings with a 5 day mean AHI and sleep graphs.

Let's face it, we're all looking for quick-fix solutions, and I'm not trying to cut corners, but I am trying to help myself whilst on the journey to losing a bit of weight.

So that I don't confuse the issue I will not intentionally lose weight until I have tried some of the other methods.

So, in essence I am looking for some way of bringing my AHI down, along with the time that I spend awake at night.

...but before I do that, how about trying to INCREASE my AHI? Next blog post.

A nightcap - Alcohol and Apnoeas

 

A nightcap helps you sleep, right?

Well, yes but...

During my initial explorations with the flow-meter, I thought that I'd test my set-up by trying to INCREASE my AHI using a well known substance that makes sleep apnoea worse...

Alcohol.

A sleep experiment where I get to have a drink or three... it's tough, but I'll do it for science. 

Pretty much as it does with people, alcohol relaxes the muscles in the airways making them more prone to flopping around all over the place and causing an obstruction.

When it comes to the rest of the practices, gadgets, fads and ideas that I'll be exploring I'll be testing them for 5 days in a row each. To be honest I'm not going to do that with alcohol as I can't afford a week of waking up sluggish and groggy. 

So, what I did was to take 5 non-consecutive days instead. I consumed alcohol and recorded my AHI on those nights along with my 5 day no-alcohol mean AHI for comparison (see previous blog).

Pretty conclusive.

Alcohol increased the number of times that I either stopped breathing or breathed so little that it was ineffective.  

Not only that, but it did it in quite a startling way. It took my 5 day mean AHI from 6.95 to 12.2.(max 15.3) To get that into perspective, that's nearly double the number of times PER HOUR that I had breathing problems.

As discussed on the post "My Baseline AHI", I went from just scraping in with a diagnosis of "Mild Obstructive Sleep Apnoea" to being firmly in the category!

Surely there was something positive to salvage from this bad news?

Yes. Annecdotally, in my mind alcohol helped me to get to sleep and I found that the Zeo data backed that up. Again, using a 5 day mean value, my time to sleep onset (or Zeo's "Time to Z") went from 28 minutes without alcohol down to 9 with alcohol.

That seemed to be the only significant difference in the data, so I haven't bothered to clutter the page with other measurements.

It may help you to get to sleep, but the chances are that the sleep will not be good sleep. The chances are that it will be disturbed sleep, the chances of having to go to the bathroom will increase, as will the likelihood of dehydration-related headaches and fragmented sleep towards the morning.

Not only would I wake up feeling slow and mildly hungover, but I'd be tired from being woken up up to 15 times an hour through apnoeas.

Don't misunderstand me, this isn't one of those damning posts about alcohol, but it is something to bear in mind if you already suffer with sleep apnoea, and it may even cause mild apnoea in people who don't have it.

Will I continue to drink alcohol? Of course, and that's the dilemma. So I guess the answer is "everything in moderation".