London: When I arrived at the sleep service at the local hospital, most people were going out for the evening. In pajamas and sheepskin boots, however, I was prepared for one of the more bizarre nights of my life – at a clinic to find out the real cause of my crippling tiredness.
For years I’ve suffered from daytime tiredness – every day. I fall asleep mid-conversation and remain in a dream-like state, pretending to be conscious. This kind of fatigue is typical of obstructive sleep apnoea, as was my dreadful snoring, which was punctuated by large gasps of air and snorts.
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Sleep apnoea is extremely common – the airways collapse during sleep, shutting off breathing for ten seconds or more. You snore as air vibrates against the soft tissue that stands in its way. Your brain automatically wakes you up and sends a signal for the airway muscles to contract again allowing you to breathe.
This can happen around once every ten minutes or, in some cases, every couple of minutes. You don’t usually remember waking up because you fall asleep again within seconds, yet feel exhausted during the day.
I had been diagnosed with obstructive sleep apnoea just before Christmas 2013 by the same sleep service at the University Hospital of South Manchester NHS Foundation Trust.
Back then, I spent the night in the hospital monitored by a device like a watch strapped to my wrist and index finger tracking my heart, lungs, and breathing. It showed that I had stopped breathing 14 times an hour, each hour, during the night.
No wonder I was shattered during the day. I was issued with a continuous positive airway pressure, or CPAP, machine. This works by forcing the airway open with a continuous flow of air into the body through a face mask.
But while my snoring had all but gone, the daylight sleepiness continued and, if anything, became worse. I mentioned it during an appointment to check my CPAP machine was working late last year.
I would often wake with unexplained scratches on my calves and feet. I had also developed dreadful, burning, itchy pain in my arms and legs before bedtime. When I mentioned this to one of the physiologists, I was told the problem could be one of the 89 known sleep disorders and she arranged for me to have polysomnography (PSG).
A monitor would record body changes such as brain waves, oxygen levels in the blood, heart rate and breathing, as well as eye and leg movements during sleep to determine what could be causing my symptoms.
I was lucky to be under the care of the sleep service already so I was able to have this done relatively quickly. Most patients with sleep issues go to their GP and have various blood tests. Some will be referred to their local sleep service, where they’re given the wristwatch test I had 18 months ago.
Only the more complex cases are offered the full body PSG, which involves sleeping with 27 electrodes on your body.
It takes around an hour to attach all the wires that track the activity of my brain and body – there were 15 electrodes on my head alone to measure electrical activity, as well as eye movements (such as flickering of the eyelids during the dreaming stage of sleep) and the muscle movements in my chin (as the face twitches, the teeth grind and then relax during dream sleep).
Sleep consists of distinct stages: ‘drowsy’ sleep, where we’re drifting off; non-REM sleep which includes light and deep sleep; and rapid eye movement or REM, sometimes called ‘dreaming sleep’. By monitoring activity in the body and brain, doctors can tell which stage of sleep you’re in. For example, during REM sleep your brain is very active.
At this stage your muscle tone – measured via the chin – also drops down because your muscles are turned off by your brain, so you don’t act out your dreams. Apparently, all this information lets doctors analyze the quality of your sleep and check if it is disrupted. read more