Sleep and Performance - Assessing Sleep

In an earlier article I discussed the importance of sleep and performance.

Many people aren't getting the adequate amount of sleep required for their bodies to function properly. While some individuals just need more sleep because of family, social, or work obligations impacting their sleep, others may have an untreated sleep disorder that keeps them from getting good quality sleep each night.

This week I investigate a method for testing sleep; a Polysomnogram. 

A Polysomnogram or PSG is a diagnostic tool to perform a sleep study and to determine if you have a sleep disorder.

This test monitors your sleep cycles and stages to identify any disturbances. You are connected to a variety of equipment to help monitor things like:

• Brain activity
• Breathing activity
• Muscle activity

A polysomnogram is used to diagnose a wide range of sleep disorders such as:

• Central sleep apnea, OSA, sleep-related hypoventilation disorders, and other sleep-related breathing disorders.
• REM behavior disorder, or other parasomnias (abnormal actions or behaviors while sleeping).
• Idiopathic hypersomnia, narcolepsy, and other hypersomnolence disorders.
• Non-24-hour sleep-wake syndrome, delayed sleep phase syndrome (DSPS), or advanced sleep phase syndrome and other circadian rhythm sleep-wake disorders.
• Bruxism, periodic limb movement disorder (PLMD), restless legs syndrome (RLS), and other sleep-related movement disorders.

So what do the results mean? I decided to undergo a sleep study to ascertain the cause of my constant fatigue first thing in the morning.

I was connected to a polysomnogram (portable diagnostic study in my home) overnight. Due to the position of the device on my chest, I was forced to sleep on my back. The tracing was measured at 30 second intervals, with the following parameters:-

• Frontal, central and occipital Electroencephalogram (EEG) - detects abnormalities in your brain waves or the electrical activity of your brain
• Electrooculogram (EOG) - records the movements of the eyes during sleep 
• Submentalis Electromyography (EMG) - measures Atonia or Bruxism 
• Nasal and oral airflow
• Electrocardiogram (ECG) - to measure disorders of the heart during sleep
• Body position
• Inductance plethysmography - to detect thoracic and abdominal movement
• Pulse oximeter - to measure oxygen saturation Sp02

The results of the Sleep study were quite interesting:

1. Sleep efficiency was normal at 87.1%
2. Sleep architecture was normal
3. All stages of sleep were achieved
4. Only a few minutes of slow wave sleep were achieved
5. Supine REM sleep was seen
6. Sleep latency and REM sleep latency were normal
7. Occasional bursts of repetitive obstructive apneas and hypopneas
8. Sleep fragmentation (AI 7.8)
9. Oxyhaemoglobin desaturation 81%
10. Respiratory Disturbance Index (RDI) 14.1 events per hour
11. REM Respiratory Disturbance Index 37 events per hour
12. Average awake oxygen saturation 94%
13. Oxygen Desaturation Index (ODI) 11.2 events per hour
14. Time spent oxyhaemoglobin saturation below 88% was 1.4% of sleep time and below 80% was 0.0% of sleep time
15. ECG was normal 
16. No periodic limb movements
17. Snoring was recorded
18. Reported sleep quality was the same as usual, with discomfort of apparatus while sleeping supine

In summary, I was diagnosed with mild Sleep Disordered Breathing (SDB). This was due to the RDI of 14.1 events per hour predominantly in REM sleep, associated with sleep fragmentation (AI 7.8) and oxyhaemoglobin desaturation to 81%.

Sleep-disordered breathing (SDB) consists of episodes of periodic obstructive or central sleep apnea and partial upper airway obstruction. 

It is to be noted that lying on your back (supine) can itself cause sleep apnea, as gravity increases the tendency for the jaw, tongue and soft palate to drop back toward the throat, which narrows your airways and can lead to breathing difficulties. Therefore, had the sleep study been performed while side-lying, the result may have been different.

In the next article I will investigate treatment options for Sleep-Disordered Breathing.