If your doctor suspects you have a sleep disorder such as obstructive sleep apnea, they will recommend a sleep test. Home sleep testing is a convenient way to determine whether you have sleep apnea. A test gathers data as you sleep, which is analyzed by a board-certified sleep doctor.
A sleep test records an array of detailed data, the vast bulk of which you will not need to see. Analysts of this data will condense the information and create a report summarizing the main results and diagnosis. Your doctor will discuss the results with you during your appointment.
In this article we will look at the main data a sleep test records and why it is relevant to a sleep disorder diagnosis. However, we will firstly take a look at how sleep patterns work.
What Are the Different Stages of Sleep?
We go through five stages of sleep through the night. The first four stages are dreamless, although our sleep becomes increasingly deeper. The final stage of sleep is where we dream, and is the rapid eye movement (REM) stage. When sleep patterns are undisturbed, we fluctuate between non-REM and REM sleep during the course of the night. When this pattern is interrupted, we can suffer the effects of sleep deprivation, such as excessive fatigue.
Measuring the Quality of Sleep
During a sleep test, the time spent sleeping during each of these stages is measured. However, the first objective measurement taken is the overall time you are asleep during the night. These initial results can often surprise people, as we often think we have slept for longer or shorter than we actually have.
Another key measurement is overall recording time, which also accounts for the time spent trying to get to sleep. On average, it takes 15 minutes to fall asleep. This period is referred to as the onset latency period, and difficulties in dropping off to sleep can be an indicator of a sleep disorder like sleep apnea. Even if you rapidly fall asleep, this could still be a symptom of sleep deprivation associated to a sleep disorder.
Data taken from the time you turn off the lights, when you finally fall asleep and how long you sleep point to your sleep efficiency. Sleep disorders will result in a reduced level of sleep efficiency, as can suffering with conditions such as stress, anxiety and depression.
One of the main symptoms of obstructive sleep apnea is frequent awakenings through the night. By measuring the stages of sleep, analysts can record the severity of any awakenings or arousals during the night. Awakenings are classed as interruptions which see you return to light sleep after 15 seconds. An interruption lasting less than 15 seconds is referred to as an arousal, and is one you are unlikely to be aware has happened.
The total number, as well as frequency, of both awakenings and arousals are recorded during a sleep test. This data provides an index, and although we all have different tolerance levels, the higher the index the more fatigued we will likely feel. Consistent sleep deprivation can have serious health implications, as well as increase our chance of accidents.
Determining Sleep Apnea Severity
A sleep test also measures blood oxygen levels. Obstructive sleep apnea sees a collapse of the airways, resulting in breathing difficulties. During an apnea airflow is reduced by 80%, whereas in a hypopnea it is reduced between 50 to 80%. A sleep test measures the amount of both these apnea events, and how frequently they occur each hour.
A respiratory disturbance index is generated from these figures. The level of breathing disturbance severity is indicated by the following index:
- Mild – index of 5 to 14
- Moderate – index of 15 to 30
- Severe – index of greater than 30
A similar scale of mild to severe is used to measure drops in blood oxygen levels, with a saturation level below 80% rated as severe, compared to a normal level of 95%.
Is It Time for A Home Sleep Test?
If you’re having trouble staying awake most afternoons, and know that you snore loudly at night, you owe it to yourself to get a sleep test. The fatigue is taking a toll on your concentration and your work -- and can lead to serious car accidents. It’s possible you have sleep apnea, which is a very treatable condition.
Home sleep testing plays an important role in the diagnosis of sleep apnea. Your doctor will use it in conjunction with observations about your lifestyle when discussing treatment options.
How your fatigue affects your daily life is a key factor in analyzing the severity of a sleeping problem. Your doctor will use all the available information to recommend a treatment course to help return you to good seven to eight hours of uninterrupted sleep.
Your body requires sufficient sleep every night to restore and recharge -- and to keep you healthy, living longer and happier.
If it’s time for a sleep test, our SleepQuest sleep care specialists are happy to discuss your sleep problems with you.