Barbara was angry. She was happy to hear that she didn’t have to spend a night in a sleep lab, sleeping in a strange bed with someone watching you all night. After watching the instructional video the night she was planning to do her study at home, she attached the finger probe, chest belt and the nasal probe as directed. As she started to fall asleep, she felt that her nose was stuffy and had trouble getting to sleep. Even when she was able to fall asleep, she kept waking up. To make matters worse, the device kept beeping and telling her to check her leads. The next day, she mailed it back to the company. One week later, her sleep doctor called to tell her that there wasn’t enough data for analysis and that she would have to do the test over again.
Granted, this is an extreme example, but I do see this happening more often than it should. Fortunately, technology has improved over the years, and many of these problems have improved as well. Some companies will have you do two or three nights in a row. Other companies have computer algorithms that can tell if you enough data for a useful study.
Most home sleep studies will measure the following 3 types of information: nasal airflow, finger oxygen level, chest/abdomen movement. Other units will also have sensors that can tell your sleep position and snoring levels.
In contrast, in-lab studies also include brain wave signals (which determine sleep stages), chin muscles activity, leg muscle activity, and oral airflow thermometer. Comprehensive testing can be done at home, but not very practical, since leads tend to fall off when you move around during sleep.
Here are 7 reasons why I prefer not to use home sleep studies and the reasons why:
1. Home studies can’t tell sleep stages. You need to see specific brain wave patterns (using scalp EEG, or electroencephalogram leads) to determine sleep stages (awake, light sleep, deep sleep, and REM sleep). Oftentimes, you’ll see that apneas happen much more often during REM sleep, especially on your back.
2. Home studies don’t measure limb movements. It’s important to see how often your legs move, as this can be a sign of periodic limb movement disorder (PLMD).
3. Home studies can’t tell arousals. Since you don’t normally see brain activity, you won’t be able to see how often you wake from deep to light sleep or wake up completely.
4. More technical problems. Since there’s no technician to come in to troubleshoot, simple mechanical problems are less likely to be solved immediately.
5. Not as good with mild disease. It’s been shown that home sleep studies will underestimate sleep apnea severity by about 10 to 20%, especially if you have mild obstructive sleep apnea. One particular reason is that an in-lab study is scored manually, with periods of wakefulness being ignored when calculating total sleep time. So if you remove the time that you’re awake from your total sleep time, the total avery number of obstructive events per hour will be higher.
6. Too many false alarms. To prevent errors when recording, these units will have built-in algorithms to sound an alarm if it detects that something is wrong. Somethings, it will keep beeping too much, leading to a bad night’s sleep.
7. Can cause more obstructions and arousals. This is a problem with both in-lab and home studies. The probe that’s placed in your nose to measure airflow is like an oxygen cannula that you use to deliver oxygen in hospitals. If you have flimsy nostrils, breathing in through your nose may cause your nostrils to cave in more, causing more nasal congestion, leading to more fragmented sleep. Having a stuffy nose due to having a cold or an allergy attack is why your sleep quality goes downhill temporarily.
There are a number of different companies that make home sleep study units, but one in particular (Itamar) is very different. It uses one finger probe that measures oxygen levels and subtle blood vessel sympathetic tone changes, which has been found to correlate very well with apneas and hypopneas. It can even report sleep stages. All the different devices have additional variations, and their pros and cons, with sleep physicians having personal preferences. Although I prefer in-lab testing, I’m OK with home testing. Some insurances require home testing.
Despite all these problems, home sleep studies can be very helpful in making a sleep apnea diagnosis, especially for patients with a relatively high chance of having obstructive sleep apnea. This technology is rapidly advancing and is likely to get better and better. There are now smart phone apps being developed using sophisticated algorhithms that may be able to calculate the number of times you stop breathing. In the Apple Watch rumor mills, it’s been even speculated that the watch can not only measure heart rate, it has technology built in to potentially measure oxygen levels.
Barbara eventually was able to undergo another home test, but this time, with lots of guidance from the home testing company, she was able to do the test properly, and was found to have moderate sleep apnea. She started using an APAP machine the following week, and is now sleeping much better every night.
If you’ve undergone a home sleep test, what are some problems that you experienced? Did it give you useful results? Was it convenient, or more of a pain? Please enter your comments below.