Sleep test

I’m really excited to introduce Dr. David Dawson and Dr. Tom Chambers—two highly respected, experienced sleep physicians who have spent their careers helping patients navigate the complex world of sleep-disordered breathing. I am grateful they have agreed for a practical, easy-to-understand discussion on the spectrum and nuances of sleep-related breathing problems.

1. My sleep study was negative, but I still snore and feel tired and unrefreshed after sleeping. How is this possible?

The reason we worry about snoring as a symptom is that it’s often a sign of sleep-disordered breathing (1). If someone is snoring and is feeling tired and unrefreshed by their sleep it could be that the sleep study was a false negative. Our sleep is dynamic and changes on a nightly basis. Night-to-night variability (NtNV) is a well described phenomenon in sleep research (2,3) and can result in a false negative study.

Exactly how sleep studies are scored is a whole story in itself, too. The reference scoring manual for sleep studies, the American Academy of Sleep Medicine (AASM) Manual (4) has undergone no fewer than 9 changes in the past 25 years! The primary changes relate to how we score ‘hypopnoea’ events, which make up part of the ‘apnoea-hypopnoea index’ (AHI). The AHI is the score we use to measure severity of sleep apnoea. It is a measure of the number of times per hour someone stops breathing (apnoea) or has a significant reduction in breathing (hypopnoea) per hour.

Most recent evidence suggests we should score hypopneas based upon ‘3% desaturation criteria’ (4) - this means scoring hypopneas when breathing is reduced and oxygen levels drop by 3% or more. The alternative way of doing this is with a 4% criteria, which can miss subtle events particularly in women, younger individuals, or people with darker colour skin (5). So it’s worth checking how your sleep study was scored if you’ve had one that was negative and it doesn’t quite match up to your symptoms.

2. Does it matter if a sleep study is recorded over one night or multiple nights?

A vast majority of the time, no. A sleep study is conducted over a whole night and there are plenty of hours of data captured to get a good assessment of someone’s breathing during their sleep. However, due to the natural NtNV of sleep disordered breathing, a single night can fail to identify the ‘true’ severity of someone’s sleep disordered breathing. Ideally we’d have sleep studies running over weeks or months but this is impractical, though devices that can do this are coming!

It’s important to say that we treat sleep disordered breathing with an eye on symptoms rather than just numbers from a sleep study. If a sleep study doesn’t quite match up with the patient in front of you we’d always be probing deeper to consider if a different test, or a study over multiple nights, or a trial of therapy is worthwhile.

3. Is sleep disordered breathing different in women and men?

Absolutely it is. It’s something that the sleep community are increasingly aware of and making steps to rectify but we’re definitely behind where we need to be. Like so many things in medicine, our approach is pretty outdated and largely based on research based on older, middle-aged males.

There are issues right across the board: from public perception, to symptom-based screening tests, and the sleep study itself.

There’s a public perception that sleep apnoea and other forms of sleep-disordered breathing only affect overweight, older men. This absolutely isn’t true and is damaging rhetoric. The real story on the prevalence of sleep-disordered breathing is nuanced. It’s classically reported that sleep-disordered breathing is more common in men than women, this is true up to a point but after the menopause this gap closes (6). We think this is due to the protective effect of oestrogen and progesterone on sleep disordered breathing. Sleep disruption during the menopause can often be caused by sleep disordered breathing and it’s something everyone should be aware of.

When it comes to screening, we often use questionnaires to predict risk of things like sleep apnoea, such as the StopBANG questionnaire (7). This focuses on loud snoring and excessive daytime sleepiness, symptoms common in men but often less so in women who are more likely to report fatigue, low energy, insomnia, or mood disturbances  (8). This can make the StopBANG questionnaire less reliable (9).

When it comes to diagnostic tests, respiratory events like apnoeas and hypopnoeas look a little different on sleep studies too, which can lead to an underestimation in the severity of sleep disordered breathing in women (10) which again is why it’s so vital to treat patients based on their symptoms not just the numbers!

There’s a great editorial on this topic from a few of years ago in the Journal of Clinical Sleep Medicine (11) - it’s worth a read here: Obstructive sleep apnea in women: scientific evidence is urgently needed 

4. What’s the difference between upper airway resistance syndrome (UARS) and obstructive sleep apnoea (OSA)?

Another great question! The lines can be pretty blurred and definitions are often changing. It really comes down to what diagnostic test is used and exactly how said diagnostic test is scored.

It’s worth first explaining the spectrum of sleep-disordered breathing (SDB). This is a collective term for many disorders which includes UARS and OSA as well as other sleep-related breathing disorders such as central sleep apnoea (CSA), sleep-related hypoventilation disorders, and sleep-related hypoxaemia disorder.

The distinction between OSA and UARS comes down to the type of respiratory events that a particular individual is experiencing that is disrupting their sleep. OSA severity is usually classified based on the number of apnoeas and hypopnoeas per hour of sleep (AHI) (12,13). It is possible to have a respiratory event (i.e. snoring or disturbed breathing) that doesn’t quite meet the exact criteria for an apnoea or hypopnea but still causes an arousal from sleep and still causes sleep disruption, this is called a respiratory effort related arousal (RERA). In strict terms, to identify a RERA you need to be monitoring brain activity during sleep, which we rarely do when it comes to diagnosing OSA because it requires having a detailed sleep study called a polysomnogram (PSG) in a sleep laboratory. When someone has lots of RERAs but not so many apnoeas or hypopnoeas, we call this UARS rather than OSA.

All of this said, the most recent guidance from the AASM (1,4) suggests any obstructive respiratory event (an apnoea, hypopnoea, or RERA) should all be used to calculate OSA severity. This removes the need to separate OSA from UARS and suggests that UARS is really a form of mild OSA. It always takes a while for language to catch up with guidance so UARS will continue to be used a lot!

Suffice to say, this is a complex area and it boils down to the fact we are constantly discovering more about the complexities and subtleties of sleep-disordered breathing.

5. When I look up UARS, the definition seems inconsistent. Why is it so confusing?

The constant updating of guidelines and language used to define events definitely contributes to this. On one hand this is great, it shows continuous development in our approach to sleep disorders. On the other hand, it can be very confusing for both patients and clinicians alike!

The other element of this is the variety of sleep studies we use to diagnose OSA these days. If everything was based on old school PSG then definitions would be more consistent. Fortunately, we have access to many more accessible sleep studies like at-home respiratory polygraphy (which is like PSG but without the brain monitoring), or newer at-home sleep tests that have recently been approved by the National Institute for Health and Care Excellence (NICE) (14). These more accessible studies don’t directly measure brain activity so therefore can’t technically detect RERAs and identify UARS. However, there are lots of signs we can look for on a sleep study that suggest someone might have UARS even in the absence of brain monitoring during sleep.

As sleep clinicians, the main thing we need to be aware of is that sleep studies are not perfect tests. As we’ve said, it’s vital to consider the patient in front of you and not just what the numbers on the sleep study show.

6. What treatments are available for sleep-disordered breathing?

It’s a really exciting time to be working in sleep medicine. There are more and more treatments becoming available to patients.

Historically, the ‘only’ option for SDB was continuous positive airways pressure (CPAP) therapy. This is still the first line for many patients. Although it can be tricky to get used to sometimes, when it works well it's an incredible treatment and is often life-changing. CPAP often has a very bad image with people assuming it's a big machine and a cumbersome and claustrophobic facemask. This really isn’t the case anymore and there are hundreds of different masks out there.

We always start with a lightweight nasal pillow mask as it’s more comfortable and treats sleep apnoea more effectively (15). It’s important to also discuss the importance of nasal breathing when it comes to using a nasal mask. Problems with nasal congestion or deviation can impact tolerance of a nasal mask. Some people suffer from nasal congestion that needs managing before a nasal mask feels comfortable. Also, many individuals with sleep-disordered breathing struggle with nasal breathing in general and need some breathing re-education to maximise comfort.

Outside of CPAP there are a growing range of options. Another commonly prescribed therapy is mandibular advancement devices (MADs). These are gum-shield-like devices fitted by dentists that help bring the jaw forward during sleep. Positional therapy is another great therapy for people who have sleep disordered breathing when they lie on their back but that goes away when they’re on their side. There are an increasing number of surgical options available and recently hypoglossal nerve stimulation (HNS) has become available on the NHS. HNS devices essentially act like pacemakers for the tongue and upper airway muscles to keep the airway open overnight.

Lifestyle changes when appropriate are also always included as treatment options. This might include improved sleep habits, smoking cessation, and weight loss. There’s good evidence that the GLP-1 receptor weight loss jabs can improve sleep apnoea in people with obesity and they are approved in America for the treatment of OSA in patients who are obese. There’s also plenty of exciting research going on regarding oral medications to directly treat OSA - watch this space!

7. I am partnering with Theta Sleep to provide my UK community quick, direct access to a doctor-led sleep service with experienced, knowledgeable clinicians I trust. Please explain what addition testing my community will receive if they use this bespoke link

It’s great to be collaborating with you on providing a holistic end-to-end sleep service for your community!

We’ve worked hard to provide a service that delivers the best parts of NHS sleep medicine care in a timely fashion directly to patients’ in their own homes. To this end our service includes:

●     A comprehensive, CQC-regulated, clinical service in-line with NHS best practice and delivered by doctors, with multidisciplinary team input and clinical safety nets for high risk patients

●     Utilising the right sleep study for the right patient integrating guidance from NHS England and NICE (rather than just blanket use of the cheapest diagnostic test)

●     A great patient experience thanks to our instant onboarding, on-demand education, triaging, and sleep study/treatment fulfilment at home and on days of the patients’ choosing

●     Hospital-grade compliance (NHS DTAC, NHS DSPT, Cyber Essentials, DCB 0129, DCB 0160, DCB 1596) that ensures all patient data is kept safe and secure.

Because of the crossover with breathing pattern disorders and subtle SDB/UARS, we’ll always make sure that anyone who books with us via your link gets a sleep study that can look for signs of UARS. We also provide a comprehensive sleep assessment to look for any other sleep disorders or areas to improve sleep health.

If anyone has any questions about our service, please get in touch via this form

Dr David Dawson

Consultant in Anaesthesia and Sleep Medicine

Medical Director, Theta Sleep

Dr Tom Chambers

Resident Anaesthetic Doctor and ESRS-certified Somnologist

Chief Medical Officer, Theta Sleep

I am grateful to Dr Tom Chambers and Dr David Dawson for their time creating this blog which I hope you have found helpful. My affiliate disclosure is here. If you would like my help re-establishing 24-hour nasal breathing click for further information on how to work with me.

May you all breathe as nature intended,

Louise : )

References

1.  AASM. International Classification of Sleep Disorders (ICSD-3-TR). Darien, IL: American Academy of Sleep Medicine; 2023. (3rd ed, text revision).

2.  Punjabi NM, Patil S, Crainiceanu C, Aurora RN. Variability and misclassification of sleep apnea severity based on multi-night testing. Chest. 2020 Jul;158(1):365–73.

3.  Roeder M, Bradicich M, Schwarz EI, Thiel S, Gaisl T, Held U, et al. Night-to-night variability of respiratory events in obstructive sleep apnoea: a systematic review and meta-analysis. Thorax. 2020 Dec;75(12):1095–102.

4.  Troester MM, Quan SF, Berry RB, Ar PDA, Alzoubaidi M, Bandyopadhyay A, et al. The AASM Manual for the Scoring of Sleep and Associate Events V3: Rules, Terminology and Technical Specifications. Darien, IL: American Academy of Sleep Medicine; 2023. (Version 3).

5.  Malhotra RK. AASM Scoring Manual 3: a step forward for advancing sleep care for patients with obstructive sleep apnea. J Clin Sleep Med. 2024 May 1;20(5):835–6.

6.  Young T, Finn L, Austin D, Peterson A. Menopausal status and sleep-disordered breathing in the Wisconsin Sleep Cohort Study. Am J Respir Crit Care Med. 2003 May 1;167(9):1181–5.

7.  Chung F, Abdullah HR, Liao P. STOP-Bang questionnaire: A practical approach to screen for obstructive sleep apnea. Chest. 2016 Mar;149(3):631–8.

8.  Saaresranta T, Anttalainen U, Polo O. Sleep disordered breathing: is it different for females? ERJ Open Res. 2015 Oct;1(2):00063–2015.

9.  Orbea CAP, Lloyd RM, Faubion SS, Miller VM, Mara KC, Kapoor E. Predictive ability and reliability of the STOP-BANG questionnaire in screening for obstructive sleep apnea in midlife women. Maturitas. 2020 May;135:1–5.

10.            Svensson M, Franklin KA, Theorell-Haglöw J, Lindberg E. Daytime sleepiness relates to snoring independent of the apnea-hypopnea index in women from the general population. Chest. 2008 Nov;134(5):919–24.

11.            Martínez-García MÁ, Labarca G. Obstructive sleep apnea in women: scientific evidence is urgently needed. J Clin Sleep Med. 2022 Jan 1;18(1):1–2.

12.            NICE. NICE guideline [NG202]: Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s. National Institute for Health and Care Excellence; 2021 Aug.

13.            Epstein LJ, Kristo D, Strollo PJ Jr, Friedman N, Malhotra A, Patil SP, et al. Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med. 2009 Jun 15;5(3):263–76.

14.            NICE. DG62: Home-testing devices for diagnosing obstructive sleep apnoea hypopnoea syndrome [Internet]. National Institute for Health and Care Excellence; 2024 Dec. Available from: https://www.nice.org.uk/guidance/dg62

15. Genta, P.R. et al. (2020) ‘The importance of mask selection on continuous positive airway pressure outcomes for obstructive sleep apnea. An official American Thoracic Society workshop report’, Annals of the American Thoracic Society, 17(10), pp. 1177–1185.

#sleep #snoring #sleepapnoea #sleepapnea #apnea #uars #osa