What's Happening in my PSG/Sleep Study?

A patient came in and brought a CD with a prior sleep study and based on their symptoms I took a look at it later and I thought this might be a good chance to take a screen shot and then show it here so you can see what an average screen looks like so you can see what I review after you get your overnight study.
This screen shot represents 30 seconds, and the average person sleeps about 6.5 hours during their sleep study, so I review on average 780 of these screen shots each time I review a study. It goes quicker than you think, mainly because I've looked at so many now.
---First, at the bottom, you can see a time-of-night bar which shows you where you are in the night. You can see on here that we are early in the night (23:10:38 to be exact if you look closely there or in the upper left corner).
---Next, you can see see the "SaO2" which shows blood oxygenation. This person is averaging 94 and 95%.
---Above that you can see "Abdomen" and "Thorax"  which are from the bands around your stomach and chest. They show movements which help characterize your breathing since there are different type of abnormal breathing patterns (i.e. obstructive apneas, central apneas, hypopneas, mixed apneas, Cheyne-Stokes... etc.)
---The "Flow" above that also helps us via assessment of airflow in your upper airway.
---Next are the "RAT" and "LAT" which assess your leg movements at night... periodic limb movements (PLMS) which can be associated with restless leg syndrome (RLS) or independent, but other abnormal movements of the limbs can be evaluated by these leads as well.
---The "ECG" checks your heart with one lead, and checks basic rhythm and gives a gross view of any premature beats/missed beats/how they may change during the night. Some people have sudden changes associated with their respiratory events.
--- "ROC" and "LOC" tell us what your eyes are doing and helps immensely with staging of your sleep such as slow wave sleep versus REM (dreaming) sleep.
--- "Snore" is self-explanatory. It's a little mic that picks it up.
--- The "Chin" lead tells us if you're having muscle movements in your chin and helps us stage sleep and look at other things like bruxism (clenching/grinding of your teeth at night)
--- The top 6 lines: "Cz-T4" "T3-Cz" "Fp1-O2" "O1-A2" "C3-A2" are the EEG electrodes placed on your head during the study. You don't have to have all the ones we have here, but because I'm a Neurologist, I pay closer attention to EEGs and often get referrals for things that happen at night concerning for possible nocturnal seizures versus other things which a few more EEG leads help you differentiate. This is the most interesting part of this particular Polysomnogram (sleep study) actually: You can see about 2/3rds of the way across that these leads show some large amplitude waves. If you look at them closely, you can see that there is a "wave" and a jagged "spike" component to each of them (maybe 8 or 9 of them total). We call these... "spike and wave" complexes. These are actually consistent with a generalized seizure this patient had during this study. Now I would need a full EEG with many more leads to characterize better... but this person didn't have breathing problems, but instead was feeling awful during the day because they kept having small seizures throughout their night.
I hope you found this interesting. I sure do.

Introduction to Sleep: Recent Article in The Triangle Physician

Click image to enlarge.

Sleep Disorders are Simple and They're Not

This diagram was given to me by a new sleep patient once. It was given to them by their prior sleep specialist at their new visit with them. Many years later, they were still suffering from poor sleep and excessive daytime sleepiness from what turned out to be a relatively straight forward cause. We were able to address it without even needing a new sleep study, just a long conversation discussing their sleep issues. Anyway, I asked them if I could make a copy because it made me laugh. How intimidating is this chart?! Why would I show someone this? It looks like the slide from some scientific meeting.

I decided that if you could understand that diagram, you could probably work this and then procede to fly off in it after I showed you the above diagram:

The reality is that yes, Sleep Medicine can be very complex. It is at the intersection of many medical disciplines: Neurology, Pulmonology, Cardiology, Otolaryngology, Psychiatry, and the implications of different sleep disorders (More than 85 different sleep disorders last count) cross-affects many different medical specialties.

But, many of these sleep disorders can be evaluated and diagnosed without requiring an overnight sleep study.

If you do need a sleep study, we essentially look at the following basic parameters:

The summary is actually pretty straight forward at this level. From top to bottom we see:
-Sleep stages (notice the stage REM dreaming in black)
-Body position (This person started on their right, then went to their back, then left... never on their stomach)
-Oxygenation (We want it to stay close to 100%. This person dropped severely)
-Respiratory events (There are many types of respiratory events. This person had mainly two types but many of them)
-CPAP (You can see it starts in the latter part of the night, and we increase the pressure to try and find one that stops or markedly improves the number of respiratory events. This person had a trend of improvement but may need more work)
-Arousals (This is arousals from all different types of things: breathing issues, leg movements, pain, bed partner snoring... although we have to figure some of this out more by discussion than this estimate alone. This at least tells us a basic idea of what all woke you up this particular night)
-Periodic Limb (leg) Movements during your sleep (not a problem for this individual)

We can check many other things as well, such as carbon monoxide levels, or we can add a full EEG to your head to look not only for sleep stages with our basic EEG, but for actual nocturnal seizures. We also do other tests for things such as Narcolepsy or for more complex sleep apnea or assessment of daytime wakefulness.

But in your average initial diagnostic polysomnogram (PSG), the fancy word for sleep study, these are the basic things we look at and utilize to help determine how an average night of sleep unfolds for you.

So I hope when you go to discuss these things with your sleep specialist physician, you can just relax and tell him or her what is going on, and let them figure out where to fly from there.