Patient guide · Sleep medicine
Overnight oximetry, a simple home fingertip test that screens for OSA and nocturnal hypoxaemia.
Overnight oximetry uses a fingertip pulse oximeter to record SpO₂ and heart rate through the night. A first-line home screen for OSA (via oxygen desaturation index) and nocturnal hypoxaemia in COPD / heart failure — cheaper than a full home sleep study.
Why patients choose us
- 01
The right hands
We route you to a consultant sleep physician — with overnight oximetry, the clinician who interprets it decides the answer.
- 02
Often answers same-week
Device dispensed, worn at home, and reported within days — no clinic overnight stay.
- 03
Independent, and free
We are paid by no clinic, so the recommendation is impartial and costs you nothing.
Key facts
What overnight oximetry is, in six lines.
A clinically reviewed summary — the definitions and thresholds that matter, without the jargon.
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Definition
Overnight home SpO₂ + heart-rate recording using a fingertip pulse oximeter.
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Oxygen desaturation index
The report’s headline number — desaturation events per hour of recording.
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ODI > 15 events/hour
Suggests significant obstructive sleep apnoea and warrants further work-up.
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Cheaper than a sleep study
Substantially less than a Type III / IV home sleep study — a sensible first screen.
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Complements STOP-Bang
Sits alongside clinical prediction tools rather than replacing them.
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Same-week private pathway
Device out, night worn, and reported inside the same week in our network.
How it works
From consultation to report — what happens, in order.
One consultant sleep physician from first message to reported study — usually within the same week.
Phase 1 · Before your night
Consultation and device dispatch
Phase 2 · The night itself
At home, in your own bed
Phase 3 · After
Analysis, review, report
- 01
Before
Sleep-medicine consultation
Consultant review of symptoms, Epworth score, STOP-Bang and cardiorespiratory history to decide if oximetry is the right first step.
- 02
Before
Device dispensed to home
Fingertip pulse oximeter couriered or collected, with written and video instructions.
- 03
On the night
Fingertip probe fitted at bedtime
Clip the probe on a finger, press start, and sleep as normally as you can — nothing else to manage.
- 04
On the night
Overnight recording
SpO₂ and heart rate sampled every few seconds through the night, stored on the device.
- 05
After
Return device next day
Drop off, courier collection, or freepost return — whichever suits.
- 06
After
Automated analysis + physician review
Software calculates ODI, mean and nadir SpO₂; a consultant sleep physician then reads the trace.
- 07
After
Report and next-step plan
A written report with a concrete next step — reassurance, formal home sleep study, or straight to CPAP work-up.
Typical end-to-end: 3–7 days. Urgent cases: same week.
What it shows
What overnight oximetry can — and can’t — tell you.
The findings a good oximetry report will speak to, and the red flag that changes the pathway.
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Oxygen desaturation index (ODI)
The headline number — desaturation events of ≥ 3–4% per hour of recording.
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Nocturnal hypoxaemia (mean SpO₂ < 90%)
Time spent below 90% saturation — relevant in COPD, heart failure and post-COVID recovery.
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Positional pattern (supine)
Whether desaturations cluster when you sleep on your back — flags positional OSA.
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Nadir SpO₂
The lowest saturation reached overnight — a marker of severity.
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Heart-rate variability (surrogate for arousals)
Pulse-rate surges suggest respiratory-event arousals when full EEG isn’t used.
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COPD nocturnal hypoxaemia
Screens for the sustained low saturations that guide home oxygen decisions.
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Post-COVID persistent hypoxia
Documents overnight desaturation in long-COVID breathlessness work-up.
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Red flag: severe hypoxia + heart failure — urgent sleep medicine / respiratory
Findings suggesting severe hypoxia in the context of cardiac disease need urgent specialist review, not a routine slot.
Treatment options
What can follow — depending on what the study shows.
The pathways your consultant is choosing between — none of these is decided by the oximetry alone.
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CPAP for confirmed OSA
Continuous positive airway pressure — the standard of care for moderate-to-severe obstructive sleep apnoea.
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Mandibular advancement device
A custom dental splint — an option for milder OSA or CPAP intolerance.
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Positional therapy
Devices and techniques to keep you off your back if your OSA is positional.
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Weight loss and lifestyle
Weight, alcohol and sleep-hygiene changes materially reduce event rates.
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Nocturnal oxygen for COPD hypoxaemia
Long-term oxygen therapy when sustained desaturation meets guideline thresholds.
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Home NIV for hypercapnia
Non-invasive ventilation for hypercapnic respiratory failure or obesity hypoventilation.
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Repeat oximetry post-treatment
Objective check that CPAP, MAD or oxygen is doing the job overnight.
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Structured sleep-medicine follow-up
Consultant-led review of symptoms, adherence and objective data.
Safety and eligibility
One of the safest tests in medicine.
Overnight oximetry is exceptionally safe — the practical points are technique, interpretation limits, and when a full sleep study is the correct next step.
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Painless, radiation-free
A fingertip clip and a soft red light — no needles, no radiation, no medication.
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Home, not hospital
Recorded in your own bed, which usually reflects your true sleep more faithfully than a lab.
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Sleep as normally as you can
No fasting or preparation. Take your usual medication and follow your normal routine.
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A screen, not a full sleep study
A negative oximetry doesn’t fully exclude OSA — a Type III / IV or polysomnography may still be needed.
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Not for central sleep apnoea
Central events without desaturation may be missed — flag heart failure or opioid use up front.
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Nail varnish and cold fingers
Both can degrade the signal. Remove dark polish and warm the hand before starting.
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Bring a symptom diary
Bed-partner witnessed apnoeas, snoring, daytime sleepiness — all sharpen interpretation.
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DVLA implications
Confirmed moderate-to-severe OSA with sleepiness has driving-notification duties — we brief you.
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A normal test isn’t always a full clear
If clinical suspicion stays high, a formal sleep study is the correct next step.
Red flags — a slot with sleep medicine, not a routine screen
- Severe OSA with sleepiness
- Occupational driving
- Heart failure with nocturnal hypoxia
- Refractory hypertension
- Nocturnal arrhythmia
- COPD with hypercapnia
- Post-COVID persistent hypoxia
- Suspected central sleep apnoea
- Obesity hypoventilation syndrome
Reading your report
An oximetry report can look intimidating. It isn’t.
Whatever the finding, the report keeps to the same four parts.
A quiet reminder
The report is written for your doctor, not for you — and that’s normal.
If you would like us to talk you through it before your follow-up, just ask.
- 01 Header
Indication and risk factors
Your details, symptoms, Epworth and STOP-Bang scores, and comorbidities that shape interpretation.
- 02 Technique
Device, sampling rate and recording time
Which oximeter was used, the sampling interval, and total analysable recording time.
- 03 Findings
ODI, mean and nadir SpO₂, HR trends
The numeric summary: oxygen desaturation index, mean SpO₂, time under 90%, nadir and pulse-rate pattern.
- 04 Impression
The conclusion: read this first
Normal, suggestive of OSA, or diagnostic of nocturnal hypoxaemia — with the concrete next step.
Recognised by major UK insurers
Cover depends on your policy and clinic; we confirm with your insurer before booking.
Frequently asked
Everything we get asked about overnight oximetry.
Quick answers on ODI thresholds, cost, referrals, and when a formal sleep study is the right next step.
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What does overnight oximetry show?
It records your blood-oxygen saturation and heart rate through the night from a fingertip probe, and reports the oxygen desaturation index (ODI), mean and nadir SpO₂, and heart-rate pattern — enough to screen for obstructive sleep apnoea and nocturnal hypoxaemia.
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How is it different from a full sleep study?
A full home sleep study (Type III) also records airflow, respiratory effort and body position; polysomnography adds EEG for sleep staging. Oximetry is a first-line screen — cheaper, quicker, and often enough to decide the next step.
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What ODI counts as abnormal?
An ODI above 5 events/hour is above normal; above 15 events/hour suggests significant OSA and usually triggers a formal sleep study or direct CPAP work-up. Interpretation always sits alongside symptoms and STOP-Bang.
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Do I need a referral?
Most sleep-medicine clinics in our network accept self-referral. We can arrange a fast-track private GP or consultant consultation first if a formal referral is needed for insurance or onward pathway.
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How much does private overnight oximetry cost?
Typical range in our network is around £150–£350 for the device and consultant-reported study — substantially less than a full home sleep study or polysomnography. We confirm a firm figure within one working day.
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What happens if the test is positive?
Depending on severity we arrange either a formal home sleep study, direct CPAP titration, or a mandibular advancement device pathway — with a structured sleep-medicine follow-up regardless.
Sources
Clinically reviewed against major guidelines.
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American Academy of Sleep Medicine. Clinical practice guidelines.
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British Thoracic Society. Guidelines for home oxygen and sleep-disordered breathing.
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NICE NG202. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation.
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European Respiratory Society. Sleep-disordered breathing statements.
Last reviewed 2026-07-30 · Next review 2027-07-30 · Reviewed by Pulse Atlas Editorial Board, .
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In practice, in London
Why private overnight oximetry moves differently in London
With overnight oximetry, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. The NHS route for overnight oximetry is thorough, but the queue is real. Most patients we speak with have been told to expect anywhere from a handful of weeks to several months, depending on their local trust and how the referral is graded. Going private in London usually collapses that window to a matter of days — often the same week if the diary allows. It isn’t about jumping a queue so much as buying time back while you still have the flexibility to plan around it.
In practice, a private overnight oximetry appointment in London means a named consultant, a proper hour in the room (or the equivalent on a video call), and a report you can actually read. Most of the imaging suites and endoscopy units we use sit within a mile of Harley Street or in Chelsea and Fulham, and turnaround on findings is measured in days, not weeks. For overnight oximetry specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
Honesty about expectations is part of the job. A private overnight oximetry appointment in London won’t change the underlying medicine — the guidelines, the consultants, and the equipment are largely the same as on the NHS. What it changes is speed, continuity, and the amount of time you get to actually talk through the findings. Everyone we route to is GMC-registered and works within CQC-regulated facilities.