Sleep studies fall into two main categories: home sleep tests and overnight studies at a sleep clinic or hospital sleep unit, which this guide is focusing on.

Because symptoms of sleep apnoea and other sleep disorders occur throughout the night, you may not be aware of all of them. So an overnight sleep study at a clinic is an opportunity for healthcare professionals to use sensors to measure things like your brain activity and heart rate during sleep – things that can’t be gauged just by looking at you.

By getting a complete, data-driven, picture of your behaviour and symptoms during a full night’s sleep, healthcare professionals can start unlocking the secrets of your sleep, and from there form a diagnosis, rule out any other health issues, and map out a treatment plan.

Home sleep tests, meanwhile, mainly monitor your breathing, so involve fewer sensors than an inpatient study at a sleep clinic. Doctors usually recommend a sleep apnoea test at home if they already strongly suspect you have sleep apnoea, so in-depth monitoring of multiple body systems is not required. You can also take an at-home sleep test to check your progress if you’re being treated for sleep apnoea. These types of tests can be done with a home sleep screening device such as the ApneaLink Air™ .

So what are the diagnostic tests you’ll have during a sleep study – and who performs them? The team looking after you during your sleep study will usually include a mix of medical technicians, assistants and nurses, who will attach the various sensors to your body. These will monitor:

• heart activity via sensors on your chest
• eye movements via sensors near your eyelids – this will indicate whether you experience rapid eye movement (REM) sleep
• electrical signals coming from your brain via sensors on your head
• muscle activity in your legs

Placing the sensors may feel a little strange, but it shouldn’t take long or be uncomfortable. If you have any allergies or sensitive skin, let the clinic know in advance. The adhesives used with the sensors can cause skin irritation, so they may need to find an alternative.

As well as the sensors, your breathing will be monitored via a nasal cannula, which consists of two small tubes that tuck inside each nostril. Your oxygen levels will be monitored by an oximeter, a small device that clips to the tip of your index finger, and your breathing effort will be measured by bands fitted around your chest and stomach. These three things are monitored to show whether or not your breathing is being interrupted while you sleep and to what degree, which is how we determine if you have sleep apnoea, and how severe it is if you do.

There’s more on what to expect when you arrive at the clinic and during your stay below, but first, how should you prepare for your visit?

Get ready for your sleep test as you would for any overnight stay away from home. The test is likely to be scheduled by the sleep physiologist or their secretary for the time you usually sleep, which for most of us is at night. If you work shifts or have a different sort of sleep schedule, let them know so they can take this into account.

While it’s good to go about your usual routine on the day of the sleep test, you may need to tweak it to help increase the likelihood of sleeping at the clinic. For example, if you usually drink a lot of coffee, tea or other caffeinated drinks, cut them out from around lunchtime. The same goes for alcohol – avoid it on the day of the test as it can disrupt your sleep too.

And although feeling excessively tired may well be one of the symptoms that has caused you to seek help, avoid the temptation to nap during the day – again this could hamper your chances of falling asleep at the clinic in the evening.

✓ Nightwear. Pick your favourite pyjamas, or whatever clothing you feel most comfortable sleeping in. And don’t forget a change of clothes for the next day!

✓ Something to read. If a few chapters of a novel or flicking through a magazine helps you nod off, bring them along.

✓ Mobile phone. You can keep in touch with the outside world while you’re at the sleep clinic, and listen to soothing music or a podcast if you wish (there won’t be a TV in the room), but as the light from your screen can interfere with sleep, avoid looking at it in the hour before bed.

✓ Toiletries. You’ll be able to brush your teeth and get ready for bed in your usual way. However some hair products, creams or moisturisers can prevent the sensors from sticking to your skin, so you may have to give them a miss. You’ll also need to remove any nail polish or false nails in advance of the sleep test, as these can also interfere with readings.

✓ Something familiar. Bringing your own blanket, pillow, or anything else that makes you feel at home (within reason!) is a good idea.

✓ Bedtime snack. If your evening ritual usually includes a nibble of something sweet or savoury, before cleaning your teeth of course, pop it in your bag.

✓ Medication. If you’re on any medication let the sleep physiologist know; they can advise you whether it is OK to keep taking it or if it is safe to stop temporarily if necessary.

On arriving at the clinic at the specified time you’ll need to report to reception, from where you’ll be taken to the room where you’ll sleep – it will look a lot like a simple hotel bedroom. You’ll then be left to change into your nightwear, ready for the healthcare professionals to start attaching the sensors and setting up the other equipment.

You can help the team check the sensors are working and secure by performing a few simple tests, such as moving your eyes, mouth and legs. It’s also wise to check the sensor wires are long enough for you to move comfortably in bed (they should be!). If you need to get out of bed once you’re attached to the equipment, a staff member can help you unplug the wires – don’t do this yourself unless you’re shown how to do it correctly, or you may affect the result of the sleep study.

Once all this has been done it’s time to sit (or lie!) back and relax before going to sleep. This is when the main part of the test will happen, but since you’ll be sleeping you might not be aware of anything going on until you wake up naturally the next morning!

However, if your initial data suggests you do indeed have sleep apnoea, the team may decide to wake you halfway through the night so you can try CPAP therapy. They can then see if using the device makes a positive difference to your remaining sleep – if it does you may wake up feeling a lot fresher than usual!

If you don’t wake up at your best, remember that even if you struggled to sleep due to the unusual environment you were in, as long as you managed to get a bit of shut-eye the sleep test should still have collected valuable information, such as your heart and breathing rates and oxygen levels while sleeping, as outlined above. The medical staff will help disconnect the equipment and remove the sensors and you’ll be free to get dressed and leave.

As mentioned above, you might have a diagnosis or be asked to try some treatment during the sleep test itself. Otherwise, after your study a physician (such as a pulmonologist or sleep medicine specialist) will interpret the results and arrive at a diagnosis – during this process they may consult other healthcare professionals for more details of your medical history or circumstances. The time that this process takes varies, but is usually within three to four weeks of the sleep test.

They’ll then get in touch to let you know what they found (if anything) and recommend the next steps. In complex cases, they’ll talk to you further about your results at a follow-up visit and again discuss what happens next, including treatment options.

You may feel nervous waiting for your results, but remind yourself it’s a big positive step forwards on the path to better sleep – and all the benefits that brings.

If you would like to start your own journey towards better sleep, contact the Resmed Sleep Clinic at ukclinic@resmed.co.uk for more information about sleep studies.

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