What is a dangerously low sleep oxygen level while sleeping?

Oxygen levels can be determined with several tools like the oximeter and more, but what do the figures mean? How can you find out how much oxygen is enough? This article takes you through the dangerous levels to watch out for and keep yourself and your loved ones safe.


Most commonly, the normal oxygen level that is found in children is 97-100%. In adults it’s 95-100%. In older adults, it’s 95-100%. The dangerous level of oxygen is below 90%.

In this article, we have discussed the following:

  • How to know if you a lack oxygen
  • Causes of low levels of oxygen

As per our testing, the best oximeter is: Zacurate pro

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What is a dangerously low oxygen level while sleeping?

It may come as a surprise, but while sleeping, you do not breathe as you normally would during the day. It is because REM sleep and brain activity cause irregular breathing patterns throughout the night. Sometimes the breathing even stops for a couple of seconds while changes occur in brain activity.

Overall our oxygen intake can decrease by 15%. Therefore, in some patients, hypoxemia can occur overnight while sleeping if the O2 drops below 90%. It is dangerous and must be treated immediately. Many pre-existing conditions cause this hypoxemia:

  • Anemia
  • Bronchitis
  • Sleep apnea
  • Lung diseases
  • Pneumonia
  • Asthma
  • Chronic Obstructive Pulmonary Disease

In some cases, oxygen falls naturally, like on an airplane, in the mountains, underwater, or due to smoking. You should know that a dangerously low oxygen level while sleeping is if it drops beneath 90%.

finger pulse oximeter

How low can your level go before you die?

While keeping your SPO2 at 95-100% is encouraged, it is not always that way. Below 90%, you should be concerned and already heading to get medical help. Below 70% is seriously life-threatening, and doctors will have you on artificial oxygen therapy at this point. Thus this is the fatal figure to keep in mind.

If we talk of oxygen volume in the air, humans normally breathe in air that has 20.9% oxygen by volume. When this decreases by even a fraction, we feel the effects. The consequences are almost always fatal when this is reduced to 8% for more than 8 minutes.

What are the dangers of readings below 80?

When you feel your oxygen is dropping, you should be on your way to the doctor. Below 80 is a serious sign that must be treated immediately. Dangers of such readings include the following:

  • Headaches: The first indicator of oncoming danger is the headache that comes with low O2.
  • Fainting: The first thing to happen when the oxygen cuts off is dizziness, followed by fainting. You will lose consciousness and should be supplied with artificial oxygen.
  • Organ failure: When low oxygen goes untreated, organs start to shut down rapidly. The damage to the brain due to less oxygen is known as cerebral hypoxia. The tissue starts to get affected over a prolonged duration.
  • Brain: The brain and heart are severely affected. The brain cells start dying after one minute of deprivation. When two more minutes pass, the neuron damage is more likely to be lasting and permanent. Five minutes is all it takes for it to become fatal.

What causes low levels?

Apart from the external environment, many pre-existing conditions can cause low blood O2 as well. Take a look at the common causes below:

  • Anemia: This condition affects the capacity of red blood cells to carry oxygen to the heart. It is caused due to low hemoglobin. The underlying condition of iron deficiency causes this, and it can be treated with supplements.
  • Asthma: Asthma can vary from patient to patient. It can be seasonal, exercise-induced, occupational, or non-allergic. For some, it can be minor. For others, it can be life-threatening and a barrier in daily life. It is caused due to narrowing of the airways or filling with mucus. It causes a lack of oxygen and shortness of breath as a result.
  • Emphysema – Among other lung conditions, this one affects the air sacs in the lungs. The air sacs weaken and even fall apart, causing the air spaces to become larger. It causes shortness of breath and low O2. Common symptoms include coughing and plenty of mucus.
  • Pneumonia – This is not a condition but rather a disease that is caused by an infection. The air sacs in the lungs are filled with mucus that causes a threat to the respiratory system. Vomiting, nausea, fever, and chest pain are the first indicators. While it can be treated, it can also be deadly for those with weak immune systems, like young children and older adults.
  • Sleep apnea: A sleep disorder that is super dangerous to an individual’s breathing. The breathing rapidly stops and starts causing serious threats to life. The common cause of this is the throat muscles and tongue relaxing when you go to sleep. The relaxed muscles constrict the airways and obstruct breathing. It is more common in people with obesity.

Normal levels by age

As you get older, your body goes through a variety of changes. One of those changes is that of oxygen saturation. Older adults will have a different oxygen saturation than that younger generations. Take a look.

pulse oximeter

Age Normal O2 level

AgeNormal O2 level
Children (0-18)97-100%
Adults (18-70 years)95-100%
Older adults (Above 70 years)95.00%

How do you know if you have a lack of oxygen?

Besides using an oximeter, there are other indicators your body tells you about its lack of O2. Take a look below.

  1. Dizziness

Feeling lightheaded or like you’re going to faint is a common symptom of low O2. You may find you cannot become stable, and your feet give way unless you sit down.

  1. Faster beating heart

When you find your heart racing so hard, you can hear the pulse rate. It can be a sign of low O2. Although it is also a sign of other things like heart attack and anxiety, you can double-check this with an oximeter.

  1. Shallow breaths

When there is less oxygen in the body, your body compensates by breathing faster to get as much air as possible. The feeling is much like what you experience at the end of a run or workout.

  1. Cyanosis

Ever notice how that crime shows always show blue lips when the patient dies of suffocation? That’s because the loss of oxygen will cause skin discoloration, a condition known as cyanosis. The blue or grey tint will appear on your lips, nails, or skin. Seek medical help as soon as possible if you notice this sign.

  1. Fatigue

Are you suddenly feeling extremely tired after the smallest of tasks? It could be fatigue caused by low oxygen. If any task feels so heavy that it leads to fainting, seek medical attention pronto.

Why do we get different readings on each hand?

Fingertip Pulse Oximeter

We indeed get different readings on different fingers as well as different hands. The readings can be altered due to many reasons. The following are some examples:

  • Nail color: If you have nail polish on any finger that you are using for the reading, it can affect the results. The oximeter takes its readings through a light emitting from through the nail and into the skin’s vessels. When this nail color obstructs this, the readings can be lower than the actual oxygen saturation level.
  • Skin pigmentation: People with darker skin color can get inaccurate results due to the obstruction in the light emitted from the oximeter.
  • Movement- Using the hand that is not your usual preference is advised since it is more likely to be inactive while you take the reading. Any movement will cause alteration to the figures.
  • Temperature- each finger might also have a different temperature that causes changes in the reading. Hypothermia can alter the figures radically.
  • Regional perfusion – Decreased perfusion can cause varied readings in varied locations of the hands. Low perfusion refers to decreased blood flow from the arteries to the extremities.

Toddler with an 88% level while sleeping

It is normal for adults and children to both experience a slower breathing rate and hence a slight drop in O2 levels while sleeping. However, it remains between 95%- 100%. Any drop below 90% is abnormal and requires immediate attention.

If your toddler is at 88 while sleeping, you should seek immediate medical help. Signs and symptoms of a child with low O2 include a sudden struggle to breathe and use stomach muscles to do so. A loss of appetite and increased heart rate are also common signs of the same.


To check your levels, here’s a great device from Zacurate.

NameZacurate Pro Series 500DL
Battery Life40 Hours
ColorRoyal black
Paint TypeSpray
What’s includedLanyard


  • It’s Amazon’s most recommended in the category.
  • The oximeter is easy to use.
  • It’s fast and accurate.
  • It comes with a lanyard.


  • Batteries will need to be changed after 40 hours, although it’s pretty standard.
  • It’s not recommended for children.
Zacurate Pro Series 500DL
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