The transitional form of sleep apnea is quite alarming and frightening, making people think that they’ll need a CPAP machine for the rest of their life.

By far the most common form of sleep apnea is the obstructive type.

The conditions that obstruct the airway don’t care whether you’ve just fallen asleep, or whether you’re two or three hours into your sleep, five hours into it, or if you get up multiple times throughout the night and then fall back asleep.

This is why someone with OSA is advised by their treating physician to use CPAP therapy the entire time they’re asleep, as in, the full seven or eight or more hours that they intend on sleeping.

OSA is not the same as transitional sleep apnea.

Transitional SA also goes by the name “sleep-onset” sleep apnea or “sleep-onset central” sleep apnea.

In central SA, the issue is not an obstructed airway. It’s the omission of the instruction from the brain to take a breath.

Though a person may have both OSA and transitional (or sleep-onset) SA, they operate independent of each other.

Transitional SA is not uncommon, and in fact, is often considered just a normal part of the phenomenon of sleep onset.

As we are beginning to fall asleep, it’s normal for breathing patterns to become irregular.

Researchers do not know precisely how the mechanism occurs, but as we are falling asleep, a transitional sleep apnea event may occur.

When we’re awake, we breathe without thinking about it. The brain sends a signal to inhale. This works best when we’re fully conscious.

As a person begins entering a sleep state, however, this wakefulness drive to take breaths declines – and the person stops breathing.

The result is an increase in the levels of carbon dioxide in the bloodstream.

Eventually the brain detects the building levels of CO2, during which there has not been a breath, and triggers wakefulness.

At this point we’re aware enough to know that we feel as though we haven’t taken a breath for a while. Which is exactly what has happened: apnea (ceased breathing).

It’s frightening, making some people think that they might die in their sleep.

Since it does not involve an obstruction of the airway, this phenomenon can occur while the individual is in any position: on their back, side, curled up, reclined up, etc.

At this point you will over-inhale upon being aroused and feeling as though your airway has been cut off.

You then settle back down and re-enter the transition between wakefulness and sleep – and these central apneas are bound to resume multiple times before you finally get past the transition and are fully asleep.

A sleep study, which can be conducted at a lab or at your home (the lab is more accurate), will determine how many disordered breathing events you have per hour on average.

It will also differentiate between disordered breathing events that are caused by an airway obstruction, a central source (brain) which may happen hours into slumber, or a transitional source (brain) at sleep onset.

Source: e-jsm.org/journal/view.php?number=91