What Is the Nasal Cycle and When Should It Be Assessed?

Author: Op. Dr. Javidan Asafov · ENT / Otolaryngology Specialist · Last medical review: 27.10.2026

What is the nasal cycle?

The inside of the nose is covered by a thin lining called the mucosa. Beneath the lining of the septum (the wall that divides the nose down the middle) and of the turbinates on the side walls of the nose, especially the inferior turbinates, lies a sponge-like network of veins that can fill with blood and empty again. When this network fills with blood, the lining swells and the airway on that side narrows; when it empties, the lining shrinks back and the airway widens.

The nasal cycle is the name for this swelling and shrinking when it happens by itself throughout the day, on the two sides in turn: while one side swells and narrows, the other shrinks and opens, and after a while the roles are reversed. The cycle was first described scientifically in 1895 by the German physician Richard Kayser; in other words, it has been known for more than a century and is part of how a normal nose works.

In the ideal form of the cycle, one side narrows while the other opens to the same degree, so the total amount of air passing through the nose changes little. Measurements in healthy noses have also shown that the combined resistance of the two sides changes little during the day or in different lying positions. This is why people are usually unaware of their own nasal cycle.

What controls the cycle?

How full the network of blood vessels inside the nose is depends on the autonomic nervous system, which governs the body functions that work without our conscious control, such as the heartbeat, sweating and digestion. The “sympathetic” branch of this system keeps the blood vessels in the nose constantly constricted to some degree. When this effect lessens on one side, the network of vessels on that side fills and the turbinate swells; on the other side the effect increases and the turbinate shrinks. This back-and-forth change between the two sides is thought to be controlled from deep parts of the brain, especially the hypothalamus; however, the exact mechanism is still being studied.

The same nervous system affects the nose in other situations too. For example, the reason you feel your nose open up during a brisk walk or exercise is that exercise increases the sympathetic effect and reduces the swelling inside the nose.

What is the cycle for?

Why the nasal cycle exists is not fully known. According to one explanation that has been put forward, the swollen, narrowed side is in a kind of resting phase at that time: air passes through it more slowly, the nasal mucus regains its moisture, and trapped dust and germs are cleared more easily. The open side, meanwhile, takes over the job of warming and humidifying the air we breathe in. It is also thought that the network of vessels filling and emptying in turn helps to produce secretions that contribute to the nose’s defences. In short, the cycle can be likened to the two sides of the nose taking turns to work and to rest.

Is it the same in everyone?

No. Sources state that most adults have such a cycle; however, fewer people show a truly regular, see-saw pattern in which one side opens as the other closes. In some people both sides swell and shrink together, and in others no clear pattern is seen. In the same person, the pattern of the cycle can change over time.

The length of the cycle also varies from person to person, and from day to day in the same person. Studies have reported that the time one side stays dominant ranges from half an hour to several hours. In a study in which nasal airflow was recorded over 24 hours, the cycle lasted longer during sleep than while awake.

The cycle also changes with age. It is usually absent or rare at birth; although the exact age at which it begins is not known, it appears during childhood. In children, cycles may be shorter than in adults, and some studies have found both sides changing together. In later life, the regular alternation between the two sides may lessen.

What happens in the nose when you lie down?

Lying on your back

When you sit or stand, gravity helps the blood in the veins of the head and neck return to the heart. When you lie on your back, the pressure in these veins rises and the network of vessels inside the nose fills a little more. This is why the nose generally feels somewhat more blocked when you lie down. In healthy noses this difference is usually small; in people whose nose is already swollen or narrow inside, it may be more noticeable. The cycle’s swings between swelling and shrinking may also become larger while you are lying down.

Lying on your side

When you lie on your side, the lower nasal passage usually narrows noticeably and the upper one opens. It has been shown that this cannot be explained by gravity alone: researchers found that, in people lying on their back, applying pressure to one side of the torso, or to the arm and leg on one side, also made the nasal passage on that side narrow and the opposite side open. This suggests that a reflex, triggered by nerves that sense pressure on one side of the body, acts on the network of vessels inside the nose. The position of the whole body, not just the head, appears to be the most important factor in this change; in other words, turning your body onto one side matters more than simply turning your head.

When you turn over onto your other side, it is often the new lower side that blocks and the upper side that opens; this is the “my nose is switching sides” feeling you notice at night. A study that recorded nasal airflow over 24 hours also found that more air passed through the upper nostril when people lay on one side. If you stay on the same side for a long time, however, the cycle can take over again by itself, and after a while the open side of your nose may change again.

Why do some people notice it more?

On its own, the nasal cycle usually does not cause troublesome blockage; what makes it noticeable is generally an additional narrowing or swelling on one or both sides of the nose. In a healthy nose, when one side swells during the cycle, the other side still lets air through easily. If one side is structurally narrow, then when the swelling phase of the cycle reaches the “good” side, the narrow side cannot make up for it and it feels as if both sides are blocked at once; when the cycle moves on to the other side, the blockage eases. Measurements have also shown that in noses with a fixed narrowing on one side, the combined resistance of the two sides rose markedly from time to time, in step with the cycle.

Deviated septum

A septum that is bent to one side narrows that side. People who have had one-sided blockage for a long time may get used to it, and often only notice their symptoms when the open side also blocks, for example during the cycle, when they lie on their side or when they have a cold. Over the years, the turbinate on the wider side may grow to fill the space; measurements have also shown that the cycle’s swings are larger on this wider side (deviated septum).

Turbinate hypertrophy

When the turbinates are enlarged and do not shrink with medication, the normal swelling of the cycle comes on top of an airway that is already narrow, and blockage is felt more easily. In these people the blockage is often on both sides and worse when lying down at night, and the lower side blocks when they lie on one side (turbinate hypertrophy).

Allergic rhinitis

Allergic inflammation makes the turbinates swell and can make the cycle’s swings larger. Because house dust mites live in mattresses and pillows, people with a mite allergy may find that their symptoms are worse in bed in particular (allergic rhinitis).

Colds and sinusitis

During a cold, the nasal lining becomes inflamed and the side that is in the swelling phase of the cycle blocks more than usual; studies have reported that the cycle’s swings become larger in upper respiratory tract infections. This is why, when you have a cold, you are more aware of your nose blocking first on one side and then on the other; this eases as the cold clears up. If long-lasting blockage comes with thick discharge, a feeling of fullness in the face and a reduced sense of smell, it needs to be assessed for sinusitis.

Using decongestant nasal sprays

Decongestant nasal sprays only give short-term relief. When they are used regularly for a long time, the nasal lining swells more as the effect wears off, and the person starts using the spray more and more often. In this vicious circle, night-time blockage and blockage that switches sides when you lie down become much more noticeable (nasal spray addiction).

Pregnancy and hormones

In pregnancy, hormonal changes can make the nasal lining swell; blockage is common and usually clears up on its own after the birth. During this time, do not use any medicine, including over-the-counter nasal sprays, without consulting your doctor. Some women also notice that their nose is more blocked on the days around ovulation in their menstrual cycle.

Dry air

In dry, centrally heated or air-conditioned rooms, the inside of the nose dries out, the mucus thickens and the feeling of blockage may increase. It has been reported that the humidity of the air can also affect how often the cycle switches sides and how large its swings are.

What helps?

Because the nasal cycle is a normal function, it does not need to be “stopped”. The aim is to reduce the factors that make the cycle noticeable and to breathe more comfortably at night:

• Keep your head slightly raised: Adding a pillow or raising the head of the bed a little can reduce how much the network of vessels inside the nose fills when you lie on your back. Raising your upper body slightly as well, rather than just bending your neck forward, may be more comfortable.
• Lie on the side that suits your nose: If one side of your nose is structurally narrow (which side is narrow becomes clear at the examination), lie on the narrow side; this keeps the more open side on top, where it tends to open up. Because the cycle can change again if you stay on the same side for a long time, it is normal to feel the need to change sides during the night. If there is no structural narrowing, any position you are comfortable in is fine. If you snore, lying on your side rather than on your back is generally recommended (snoring and sleep apnea).
• Rinse your nose with saline: This clears away secretions and allergens and moistens the inside of the nose. Rinsing before bed can bring relief at night. Use a ready-made solution, or one prepared with boiled and cooled or sterile water.
• Watch the humidity in the bedroom: In a very dry room, raising the humidity in moderation can bring relief; too much humidity encourages mould.
• Reduce allergens in the bedroom: If you have a house dust mite allergy, washing your sheets and pillowcases often and having fewer carpets and dust-collecting items in the bedroom can help. Treatment of allergic rhinitis is planned on your doctor’s advice (allergic rhinitis).
• Do not rely on decongestant sprays: These sprays only give short-term relief; with regular use, they can make the nose more blocked (nasal spray addiction).
• Stay away from irritants: Cigarette smoke and strong smells can irritate the nasal lining and increase blockage.

When should it be assessed?

Blockage that switches sides when you lie down and opens when you turn over is usually an expected result of the nasal cycle and the position you lie in; there is no need to worry about it. An examination is recommended in the following situations:

• If the same side is always blocked: If the blockage is constantly on the same side, regardless of your position or the time of day.
• If your sleep and daily life are affected: If you sleep with your mouth open, wake up with a dry mouth in the morning, or the blockage disturbs your sleep.
• Snoring and pauses in breathing: If you snore, or someone close to you has noticed that your breathing stops during sleep (snoring and sleep apnea).
• If you cannot stop using a decongestant spray: If you cannot sleep without the spray, or are using it more and more often (nasal spray addiction).
• Accompanying symptoms: If you have repeated bleeding, or a bloodstained, foul-smelling discharge, from only one side of your nose, if your sense of smell has clearly decreased, or if you have pain or swelling in your face, do not put off an examination.

Most of these symptoms are not caused by a serious disease; an examination helps to identify the cause and choose the right treatment.

What is checked at the examination?

The assessment starts with a detailed history: you will be asked which side the blockage is on, whether it changes with position and during the day, how long it has been going on, and about decongestant spray use, allergy, snoring and any past injuries to the nose. Then the inside of the nose is examined endoscopically with a thin camera; any septal deviation, the size of the turbinates, the appearance of the lining, and any polyps or signs of sinusitis are assessed.

The phase that the nasal cycle is in at that moment is also taken into account during the examination. The side that is swollen at that time may look narrow even when there is no structural narrowing. This is why, when needed, the nose is examined again after the swelling inside it has been temporarily reduced; this makes it possible to tell how much of the narrowing is due to temporary swelling and how much to structural causes, such as a deviated septum or bony enlargement of the turbinate.

Imaging such as a CT scan is not needed for everyone; it may be ordered if sinusitis or polyps are suspected or if surgery is being planned. If allergy is suspected, allergy tests may be done.

If there is a structural cause: septoplasty and turbinate reduction

There is no operation for the nasal cycle itself; the cycle is a normal function of the nose. Surgery aims to correct a structural problem that makes the cycle noticeable and causes symptoms. In a suitable patient, the following options may be considered:

• Septoplasty: The bent parts of the cartilage and bone are straightened to open the airway. The operation is performed from inside the nose, leaves no external scar and does not change the outward appearance of the nose. An expert consensus statement defines septoplasty as an operation that corrects a deviated septum; where the turbinates are also enlarged, it can be combined with turbinate reduction (deviated septum).
• Turbinate reduction: The volume of the enlarged turbinate is reduced while its function is preserved. When the lining is enlarged, methods that preserve the lining, such as radiofrequency, can be used; when bony enlargement is the main problem, methods that reduce the bony part of the turbinate can be used (turbinate hypertrophy).

The nasal cycle usually continues after these operations. In a study that recorded nasal airflow over 24 hours before and after septoplasty, patients rated their nasal breathing as better after surgery, and the cycle continued and was more evenly balanced between the two sides. In turbinate reduction, too, methods that preserve the function of the turbinate are preferred; after methods that shrink the turbinate with heat beneath the lining, the rhythm of the cycle has been reported to be preserved, while its swings may become smaller. Removing most of the turbinate is not preferred, because it can disrupt the cycle and the nose’s ability to humidify the air.

Once the narrow side has been opened, the other side can still let air through when one side swells during the cycle, so the cycle is usually less noticeable than before. Accompanying conditions such as allergic rhinitis do not go away with surgery; if present, their treatment continues. The decision on surgery is made together, based on your symptoms and the examination findings.

Frequently asked questions

Is the nasal cycle normal? Yes. The nasal cycle is the alternate swelling and shrinking of the turbinates on the two sides during the day, and it is seen in most adults. The cycle is regulated by the autonomic nervous system; because one side narrows while the other opens, total airflow usually changes little and most people do not notice it. It does not follow the same pattern in everyone; there are also people in whom both sides change together or in whom no clear pattern is seen. The cycle is not a sign of disease; however, if one side of your nose is always blocked or the blockage affects your sleep, an examination is recommended.

Why do I notice it more at night? There are several reasons for this. When you lie on your back, the pressure in the veins of the head and neck rises and the network of vessels inside the nose fills a little more; when you lie on your side, the lower side tends to block and the upper side tends to open. The cycle’s swings may become larger while you are lying down, and because the cycle lasts longer during sleep, one side may stay blocked for longer. The dry air of the bedroom can increase the feeling of blockage, and allergens you come into contact with in bed, such as house dust mites, can also make the nose swell. On top of that, during the day our attention is on other things, whereas at night, in the quiet, as we try to fall asleep, we focus more on our nose. This is why blockage that switches sides when you turn over is usually normal.

Which side should I lie on? If one side of your nose is narrow because of a structural cause such as a deviated septum, lying on the narrow side, so that the more open side stays on top, often makes breathing easier, because the upper side tends to open. If you lie on the other side, the open side underneath swells while the narrow side on top cannot open enough, and the nose may feel completely blocked. Because the cycle can change again if you stay on the same side for a long time, it is natural to change sides during the night. If there is no clear narrowing, any position you are comfortable in is fine. If you snore, lying on your side rather than on your back is generally recommended (snoring and sleep apnea).

Does the cycle disappear after surgery? No, that is not what is expected; the aim of surgery is not to get rid of the cycle but to correct the structural narrowing that causes the symptoms. In a study that examined the cycle before and after septoplasty, the cycle continued after surgery and was more evenly balanced between the two sides. Once the narrow side has been opened, the other side can still let air through when one side swells, so the cycle is usually less noticeable than before. Some blockage for a while in the early period after surgery, caused by swelling and crusting inside the nose, is an expected part of healing; the improvement in breathing becomes clearer as the swelling goes down.

Does it happen in children too? The nasal cycle is usually absent or rare at birth; it appears during childhood and changes with age. In children, cycles may be shorter than in adults, and in some children both sides swell and shrink together. So if your child’s nose is sometimes blocked on one side and sometimes on both, this is not in itself a cause for concern. Constant nasal blockage and mouth breathing during sleep, snoring, restless sleep or a long-lasting runny nose may suggest enlarged adenoids (adenoids and tonsils in children). A foul-smelling discharge from only one side of the nose, on the other hand, may suggest an object stuck in the nose; in this case, do not put off an examination.

Is a decongestant spray the answer? No. Decongestant nasal sprays only give short-term relief. Because the nasal cycle is a normal function, it does not need to be stopped with medicine. With regular use, the nose can become more blocked as the effect of these sprays wears off, and the person may start using the spray more and more often (nasal spray addiction). If blockage when you lie down bothers you, simple measures such as raising your head slightly, lying on the side that suits your nose and rinsing your nose with saline can bring relief; if the blockage continues, finding the cause through an examination makes it easier to choose the right treatment.

This article is for general information; please consult your physician for diagnosis and treatment.