need help recording my own core body temperature overnight (rectally!)
December 18, 2014 11:57 PM   Subscribe

I need a reliable way to measure my core body temperature while I am sleeping, so I can review the data when I awaken. The sensor needs to be rectal.

I suffer from severe DSPD, and will be mounting an attempt to shift my sleep cycle over the holidays. I have an appropriate light therapy device.

I have made a few attempts in the past but with limited success. One possibility is that I have been administering the light therapy during the wrong phase of my circadian rhythm, which may lead to ineffective or counterproductive results.

The body's temperature undergoes a periodic variation, reaching its lowest point (nadir) an hour or two before one usually awakens naturally. Light therapy administered soon after this nadir will have the biggest effect in advancing the circadian rhythm (desired in my case). Administering the light before the nadir will have the opposite effect (if anyone is interested in learning more about this, here is a very readable paper).

Now, in order to give myself the best chance of success, it would be invaluable to be able to obtain real time core body temperature measurements that are recorded while I sleep. That way, when I wake up, I can verify that I'm passed the nadir.

The challenge is that skin body temperature measurements are not well correlated with core body temperature. It's not just as if they're consistently higher or lower than the core body temperature, but they're out of phase too. As such, a wearable device that goes around my wrist or arm will not do the trick.

Oral and rectal measurements, however, correlate quite well. I can't see how I'd be able to sleep with a sensor inside my mouth (but am open to suggestions), so that leaves rectal.

Specifications for such an instrument aren't too extreme. The core body temperature varies about half a degree to a degree (celcius) over a 24 hour period. It would be nice to have a sensor that has a precision of 0.1 celcius, and can take readings every 10 minutes or so.

I'm willing to build such a system myself, and it would be good motivation to learn Arduino and some basic circuit building.

It would be wonderful, however, if a pre-built device existed, and hence this post! Does anyone have any suggestions, however hairbrained, that may aid me on this brave quest?
posted by spacediver to Technology (16 answers total) 1 user marked this as a favorite
 
I just sent you a longer email, but for the sake of the record, such a device exists and is called Vitalsense. I don't know if it's available to consumers though.

http://actigraphy.respironics.com/devices/vitalsense/
posted by feets at 12:34 AM on December 19, 2014


YOu might want to look into devices intended for woman who wish to monitor their basal temperature (usually called basal thermometer) - they are made to be used in humid places in ones body.
A google picture search for basal thermometer includes models possibly small enough to wear?

Or google for pics of or with rectal thermometer - I am at work so this is not a good search term just now.
posted by 15L06 at 12:34 AM on December 19, 2014


p.s. From my anecdotal experience, you probably don't want to use a light box simultaneous to doing chronotherapy (by which I mean, you don't want to use it while you're advancing your sleep/wake hours every day). I think when you do that you get on the wrong side of the temperature nadir. It does help to use the light upon waking about a week after finishing the chronotherapy, though.

p.p.s. I've never been able to make the chronotherapy-induced new sleep/wake times stick very long. I guess the trick is that once you get your sleep/wake times where you want them, you're supposed to never, ever stay up past bedtime again. Which is hard!
posted by feets at 12:47 AM on December 19, 2014


Response by poster: thanks for the replies. The vitalsense is an interesting one, probably similar to the one used in this study. But the vitalsense pills are $77 a pop, although they may be reusable. Also, not sure if you need the $4000 dollar monitoring device to collect data.

As for using the lightbox simultaneously to chronotherapy I'm not planning on using chronotherapy (if by that you mean some form of sleep restriction therapy). I'm using the lightbox as a sole means to shift my clock. Monitoring my temperature will ensure I'm not on the wrong side of the nadir. If that doesn't work, I might try what you recommended, though sleep restriction therapy has never worked for me. Appreciate the email btw :)

The basal thermometer idea may prove fruitful, thanks for the suggestion!

Been doing a bit more reading - seems that a rectal thermistor probe may be the way to go.
posted by spacediver at 1:00 AM on December 19, 2014


A useful search term may be "data logger."

There are many types available; some have a base unit with probes, others are one-piece USB sticks.

These will mostly be designed for monitoring rooms but you may be able to find one that meets your precision requirement and has a reasonable size and shape.
posted by mountmccabe at 1:12 AM on December 19, 2014


Putting aside the fact that on face reading this sounds like a lot of hassle, my wife tells me that there exists a Foley catheter with a temperature probe, which would do what you ask.

This is not to say that they would be available easily, but hey, you never know.
posted by Sternmeyer at 3:24 AM on December 19, 2014


Of course you would need the monitoring equipment too.
posted by Sternmeyer at 3:27 AM on December 19, 2014


I am shocked this hasn't come up yet -- having an indwelling rectal probe is going to affect your sleep, and not for the better. This isn't an assumption based on "lol butts" -- I've had indwelling rectal tubes for medical reasons and you really never stop being aware of it, and sleep is interrupted (though admittedly not impossible). For this reason, using an indwelling rectal probe while you're sleeping may be counterproductive to your goal.
posted by telegraph at 4:35 AM on December 19, 2014 [3 favorites]


I don't have a device to suggest, but continuous tympanic core temperature probes also exist and may provide another route which might be easier to sleep with in place. This might provide a starting place for something hackable if you can get hold of the pieces. Good luck with solving your sleep issues!
posted by Northbysomewhatcrazy at 5:25 AM on December 19, 2014 [1 favorite]


Response by poster: wow, great replies, much appreciated!

telegraph, yea, that's a bridge I'll have to figure out once I start to cross it. Tho I reckon something like this might be less uncomfortable.
posted by spacediver at 10:53 AM on December 19, 2014


I would really agree with telegraph. In all seriousness, you might get a buttplug and make sure you can sleep with something up there all night before you go too far down this path.

Have you exhausted more conventional sleep cycle detectors like the better ones in this article or this??
posted by Candleman at 1:58 PM on December 19, 2014


Response by poster: I've used the zeo before to assess the quality of my sleep (my sleep quality is excellent, it's just falling asleep at the right time that's an issue). I'm not interested in tracking my sleep cycles, but my circadian rhythm.

Butt plug may be a good idea. If I can handle one of those, then I can most likely handle a thinner probe.

Oh the things I do for you, dear self.
posted by spacediver at 2:13 PM on December 19, 2014 [1 favorite]


Response by poster: just a followup, ended up building a system myself with arduino.

I used the waterproof version of the DS18B20 sensor, and this tutorial.

Probe wasn't super comfortable, though not unpleasant enough to prevent me from sleeping.

Here are data from the first night. Y axis = degrees celcius, X axis = time in hours.

Next step is to figure out how to interface this with Matlab (which is the only language I know how to code in), and then I can even program an alarm to wake me up shortly after nadir if necessary.
posted by spacediver at 10:01 AM on December 24, 2014 [1 favorite]


Greetings, spacediver! I, too, once decided to stick a temperature probe up my butt and log my core temperature while I slept. (This was about a year ago; I wanted to do so primarily because I seemed to not maintain a good body temperature during sleep—I logged the room temperature every night and would wake up really hot sometimes while the room was nice and cool, or feel comfortably cool when the room was actually a bit warmer, etc..)

However, I never ended up going through with it, because this video of a lecture on measuring and maintaining core body temperature led me to believe that rectal temperature isn't a reliable measure of core temperature. It's a good watch if you're serious about measuring your core temperature. (Let me know if you figure out a good way to do it!)

P.S. Ultimately, my temperature regulation problems seem to have improved significantly from melatonin 9–12 mg (I use these) each night before bed. Based on what I've read, it sounds like melatonin can be useful for adjusting one's circadian rhythm and that most people probably shouldn't need more than 3–6 mg per night. (I appear to require more for whatever reason—my pineal gland is pretty thoroughly calcified, but that's apparently not particularly uncommon.) Anyway, you might consider melatonin supplements if you haven't already.

Lastly, I'm not a huge fan of the idea of instant-release melatonin, since it appears that melatonin is released fairly steadily throughout the night in healthy sleepers, and melatonin has a very short half-life (<1 hr?). Good luck!
posted by rbw at 11:58 AM on December 29, 2014


Response by poster: hi rbw, thanks for the response. I watched the first 3 min of that video, and I'm gathering that these issues aren't relevant to my particular context. It's true that rectal temperature has a lag time relative to core body temperature (temperature of blood in pulmonary artery is the gold standard), but as far as I understand, this is only relevant in the context of rapid and transient changes in core body temperature.

More importantly, studies that have examined the phase response curve to light, relative to core body temperature (and whose findings form the guidelines of light therapy for circadian rhythm disorders), have done so using rectal temperature.

So, even if it turns out that rectal temperature is out of phase with core body temperature (as measured via pulmonary artery), it wouldn't matter, as the phase response curve of light has been defined with respect to rectal temperature (and I don't think it is out of phase, unlike, say, axillary temperature).

I can definitely see how in your case, rectal might not be appropriate, given that you are interested in tracking the (non circadian) variations in body temperature.

I have tried melatonin in the past, both quick release and timed release. I think the quick release worked better, but I didn't find it worked very well for me. Often it would put me to sleep early enough but I'd wake up throughout the night. Here is data from a couple years ago - day 13 is when I switched to quick release melatonin. Green = awake, black = sleep, yellow = white light therapy, blue = melatonin, gray = nap, brown = chocolate bar :)

btw, here is data from the last six days. On days 3 and 4, I programmed an alarm to wake me up 1 hour after the nadir.

I've also learned how to rig the probe for comfort. Using enough slack in the probe wire, some duct tape, and looping part of the slack around my upper thigh, I can move and roll about in bed (and stretch my legs any which way with full range of motion), and not experience any tension whatsoever on the portion of the wire nearest to probe. Under such conditions, after a few minutes of inserting probe, I can't even tell it's in there!
posted by spacediver at 10:31 PM on December 29, 2014 [1 favorite]


Response by poster: sorry, in the data from 2 years back, gray wasn't napping, but lying down and resting mind while remaining awake.
posted by spacediver at 10:40 PM on December 29, 2014


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