The phrase "sleep study" doesn't refer to a learn-while-snoozing technique, but to a medical procedure (known technically as a polysomnography) used to diagnose various sleep disorders. It involves having the patient attempt to sleep all night while wired with electrodes and other sensors to collect lots of data that can be analyzed to detect indications of particular problems such as sleep apnea. This is an account my second sleep study, on the night of 31 January 2006.
A few years ago my wife, my doctor and I decided that my snoring and sleepiness might warrant medical investigation. I made an appointment with a sleep specialist, Dr. Ravenscraft. (Isn't that a great name for this sort of work?) On her recommendation I had my first sleep study in January of 2003, and it confirmed moderate obstructive sleep apnea. My treatment began with a CPAP machine. This is a device that pumps air through a respirator-like mask into one's airways all night. Though it may seem surprising that one could sleep at all while using such a device, a great many people find it quite helpful in relieving sleep apnea and similar disorders. It it isn't clear how much it really helped me, but the various masks I tried using all caused problems for me, apparently due in part to the peculiarities of my facial structure--and I do not mean my splendid mustache.
After trying a series of CPAP masks over the course of nearly two years, I switched to using a dental appliance in March of 2005. This is a device rather like a mouth guard that pushes the lower jaw forward a bit to expand the airways. I found this easier to tolerate than the CPAP masks, but even after months of adjustment I wasn't satisfied with the results, so we scheduled another sleep study, along with a "nap study" (or "multiple sleep latency test") on the following day. The nap study involves trying to take naps several times during the day to see how long it takes to fall asleep. This gives an objective measurement of daytime sleepiness.
It happened that my son John had a sleep study just a few weeks before my recent one, and he cleverly arranged to get some photos. I thought that was a great idea, so I decided to take along my trusty old two-megapixel digital camera, the one I use for tossed-camera aerial photography.
My appointment was at 8:00 p.m. on 31 January 2006 at the sleep clinic in the Meadowbrook Building, which is attached to Methodist Hospital in St. Louis Park, a suburb of Minneapolis. The clinic is on the third floor, and the clinic door is locked at night, so I pressed the buzzer to announce my arrival. Jayson, the technician who was to conduct the study, opened the door for me and took me to a small room near the entrance where he took my picture for the medical record--perhaps to prevent ringers from standing in for patients. (Oddly enough, the camera he used was the same model I had brought, an Olympus Camedia D-390.)
The rooms of the clinic flank a corridor that may be narrower than any I have seen of comparable length. In the photograph here, there are twelve sleeping rooms on the right side of the corridor. On the left side there are a half-dozen bathrooms with showers, about as many prep rooms (where patients are fitted with electrodes and such), and a control room where the technicians use numerous computer screens to monitor the sleep studies.
Jayson took me to Room 9, my room for the night and for the nap study. Besides a bed, these rooms are furnished with nightstands, a television, a small closet and a desk to provide a few of the comforts of home. As the pictures show, these rooms look more like small hotel rooms than hospital rooms. (The purple pillow is one I brought from home. Also, I somehow overlooked how crooked the lampshades were while I was there, only noticing this detail when I looked at the photos later.)
There were a few strange details, such as the equipment near the head of the bed and the video camera on the ceiling at the opposite end of the room. I didn't even think to ask why this small room was equipped with a large electric fan, but maybe some people find it easier to sleep with some background noise--or turbulent air flow?
Watch This Space
I was assured that the camera would be on only when the lights were out for sleeping, to monitor general body position (e.g., sleeping on one's back, which tends to aggravate apnea in many people).
In the close-up photo showing the video camera, the object on the right is an array of LEDs that provide infrared illumination when the lights are out, but here the LEDs are off. When they were on, the human eye could see only a faint red glow from each LED. But it happens that many digital cameras are sensitive to the sort of infrared light produced by these LEDs, and the next photo, taken when the LEDs were on, shows the purplish-white color that typically registers when such cameras receive this light. (Most remote controls for home TVs, DVD players and such produce similar infrared emissions that can be viewed on the screen of a digital camera.)
You Will be Assimilated
After I unpacked my things and got into my pajamas, Jayson came and led me to a prep room where he attached the usual electrodes and sensors:
- Electrodes taped my face to monitor eye and jaw muscles
- Electrodes glued to my scalp for the EEG that indicates various stages of sleep
- Electrodes over my collarbone to monitor heartbeat
- Bands around my chest and abdomen to monitor breathing
- Motion sensors strapped to each ankle to check for restless legs syndrome
Wires from all of these devices were bundled up and clipped to my collar.
I returned to my room for a period of quiet time to get somewhat accustomed to being so wired up. I did some reading, took some pictures, phoned home to say goodnight to Peg, and called Jayson shortly after 10:00 to have him hook up the rest of the sensors so I could go to bed:
- A vibration sensor taped to my throat to detect snoring
- Sensors attached to the end of my nose to measure air flow and temperature
- An oximeter (a device that measures blood oxygen level) clipped onto the end of my left index finger
Did I forget to mention that there was also a microphone on the wall, to listen for snoring?
Once Jayson had all my wires plugged in through a box hanging on the head of the bed, he was kind enough to take a picture. The oximeter isn't shown, but you can see its cable draped across my left hand. Don't I look comfortable?
Jayson turned out the lights and went to the control room, but it wasn't quite time to sleep yet. First he called into the room through the speaker phone on the nightstand and gave me instructions for some eye movements, breathing, and legs movements so that he could check the sensors. Then I could try to sleep.
Would it surprise you to learn that I didn't seem to sleep well? I actually slept for a total of about five and a half hours over the nearly eight-hour sleep period. I was aware of waking several times, and I turned from one side to the other five times during the night; at home, I typically turn only once or twice. Around 4:30 a.m. I pulled the call cord to summon Jayson so that I could go to the bathroom. He was able to leave most of the wires connected to a box that he hung on a lanyard around my neck so I could get up. The whole process took less than 10 minutes.
I slept little after that, but I managed to fall asleep just a few minutes before Jayson awakened me. This was just after 6:00 a.m., the official end of the sleep study. He removed all the sensors, but left the numerous electrodes, which would be needed for the nap study, and he again bundled up the wires to hang them from my collar. I got dressed, moving the wire bundle to my shirt collar, and the clinic provided breakfast in my room.
My first attempt to nap was at 7:30. Eugene, one of the daytime technicians, led me through the process. I stayed dressed, but got in bed in the darkened room and tried to sleep for the 20-minute nap interval. I didn't sleep. This exercise was repeated about every two hours, concluding around 1:45 p.m., and I stayed awake during all four nap intervals, despite my poor sleep during the night, and despite trying to relax. My daytime drowsiness often comes later in the afternoon, but it isn't uncommon around 1:30. Can I blame the electrodes for keeping me awake, despite my nighttime sleeping?
Between nap attempts I did some reading, wrote some notes, listened to some news and music, took some pictures, and went for some walks. I walked the halls on several levels of Methodist Hospital, and even put my coat on and walked outside on the hospital grounds for a while. Of course, I still had electrode wires hanging all over my head, but I didn't feel terribly self-conscious about them, mainly because I was at a hospital, after all.
I was pleased to find a beautiful painting of a great blue heron off the main lobby of the hospital. I love these grand birds--we see them often in our neighborhood, as we live only about a mile from the Minnesota Valley National Wildlife Refuge, and they feed in many of the local ponds and lakes. The painting, titled Ardea (the genus of the bird) is by a local artist, Paul Benson, and it was one of several of his fine paintings displayed in the hospital.
Lunch was served after my 11:30 nap attempt. I was surprised that it arrived with a little arrangement of flowers--four alstroemeria blossoms in a small glass bottle. The whole thing was barely more than four inches tall, but it was a nice touch--and the food was pretty good too.
After my 1:30 nap time, Eugene removed my electrodes, using acetone (or something similar) to unglue the ones stuck to my scalp. I packed my things--including the flowers--and headed home.
Two weeks later I had an appointment with Dr. Ravenscraft to hear about the results. The study showed almost no sleep apnea as such, but numerous brief "snoring-related" awakenings (technically, these are known as RERAs, Respiratory Effort Related Arousals). There were 93 of these during the night, so they constituted a significant amount of sleep disturbance. A consultation with the dentist who fitted the appliance I use indicated that we really couldn't adjust the device any further without causing jaw or bite problems, so I don't yet know how treatment will proceed. The options include continuing the less-than-ideal use of the dental appliance, going back to the CPAP machine, or possibly surgery (depending on the exact nature of the respiratory obstruction, which hasn't been established).
In recent weeks I've started doing a few all-night audio recordings while sleeping, to try to gauge my snoring. I use an inexpensive lapel microphone to record monaural audio directly to my computer, where I can scan a graphical display (instead of listening for hours) to try to spot periods of snoring. This seems to be one of the simplest at-home ways to measure possible sleep disturbance, and it has already provided some evidence that my snoring is much worse when I sleep on my left side than when I sleep on my right side. So maybe I can sleep somewhat better just by trying to stay on one side most of the time.
Last update: 2006-03-05