Is it better to sleep on your side or back? Which is healthier?

For a healthy adult, there's no single best position: both side and back sleeping can be normal. The choice varies depending on the specific problem. For snoring and especially positional obstructive sleep apnea, the side is usually preferable. For heartburn, sleeping on the left side is most appropriate. For some types of lower back pain, either a supine position with support under the knees or properly organized side sleeping can be comfortable. During the second half of pregnancy, the side is preferred. [1]

If you don't have any medical conditions or nighttime symptoms, forcing yourself to switch from back to side or vice versa is usually unnecessary. It's much more important that your sleeping position doesn't cause pain, numbness, or frequent awakenings, and that your pillow and mattress allow you to maintain a comfortable position for your head, neck, and spine. Research on the connection between sleeping position and back pain is significantly weaker than popular articles often portray: most of the data is observational, and high-quality comparative studies are few. [2]

Therefore, the question "which is healthier—the side or the back?" is best answered not by a general ranking of positions, but by purpose. For breathing during sleep, the side is often preferred; for reflux, the left side; during late pregnancy, either side; and for some people with lower back pain, the back with knee support works well. If a person sleeps well on their back, doesn't snore, has no apnea, heartburn, or pain, there's no medical reason to necessarily switch to the side.

Why does body position during sleep matter?

During sleep, a person spends several hours at a time in a horizontal position, so posture can influence the geometry of the upper respiratory tract, pressure on individual joints, the position of the spine, and the movement of stomach contents relative to the esophagus. However, the influence of different mechanisms varies: for sleep apnea and gastroesophageal reflux, it is significantly better documented than, for example, for the prevention of common neck pain in healthy individuals. [3]

People also don't lie still all night. In one large study with objective position recording, adults spent, on average, about half their time on their sides, more than a third on their backs, and significantly less on their stomachs; positions changed repeatedly throughout the night. Therefore, the goal is usually not to maintain a strict position for eight hours. [4]

For a healthy person, such rotations are a normal part of sleep. If a person falls asleep on their side and wakes up on their back, this fact alone does not indicate a disorder and usually does not require any special adjustments.

Side Sleeping: When It Actually Has Benefits

The most compelling benefit of side sleeping relates to sleep breathing. When lying on your back, gravity causes the tongue and soft tissues of the pharynx to shift posteriorly. In people with obstructive sleep apnea, this can increase the number of episodes of partial or complete airway obstruction. The Mayo Clinic, in its 2025 update, recommends that people with apnea try to sleep on their sides or stomachs rather than on their backs. [5]

Sleeping on the side is also particularly important for nocturnal gastroesophageal reflux. Here, it's not just the side that's important, but the left side. A systematic review and meta-analysis found that in patients with reflux disease, the left lateral position reduced the time acid was exposed to the esophagus and accelerated acid clearance compared to the right lateral and supine positions. However, the review included a small number of studies, so this effect should not be interpreted as a universal treatment for reflux. [6]

Side sleeping can also be comfortable for the spine if the body is well supported. The Mayo Clinic recommends slightly bending the legs and placing a pillow between the knees for back pain; this helps keep the pelvis, hips, and spine in a more aligned position. [7]

But the assertion that "sleeping on your side is always better for your spine" would be too strong. A review of studies on posture and spinal symptoms found only four relevant studies and explicitly noted a lack of high-quality data. A more recent systematic review from 2025 concluded that properly supported side and supine positions can both be acceptable for low back pain, while sleeping on your stomach appeared less beneficial. However, the included studies were primarily observational, so causality remains uncertain. [8]

Back Sleeping: Why It's Not a 'Bad Position'

For a person without apnea, severe snoring, nocturnal reflux, or any other contraindications, sleeping on the back is completely normal.

The benefit of this pose is that the body weight is distributed relatively symmetrically, and the limbs do not press against each other. For lower back pain, a pillow under the knees can reduce tension in the lumbar region and help maintain the natural curve of the lower back. This is the pose recommended by the Mayo Clinic as one of the possible poses for back pain. [9]

A recent 2025 systematic review also found an association between back sleeping and better outcomes for low back pain, while also noting the benefits of a properly supported lateral position. However, the review included only six observational studies, so it's impossible to conclude from these data that back sleeping prevents pain. [10]

The main drawback of sleeping on your back is related to your airway. For some people, this position significantly increases snoring and sleep apnea. Therefore, the same position can be comfortable for the lower back but unfavorable for breathing.

Side or back when snoring

If a person snores, the side is often preferred over the back. This is due to the position of the tongue, soft palate, and pharynx: on the back, the tissues are more easily displaced backward, narrowing the airway. [11]

However, it's important not to use posture changes as a way to rule out sleep apnea on your own. Snoring alone doesn't necessarily indicate apnea, but loud, regular snoring combined with pauses in breathing, snoring, or choking at night, severe daytime sleepiness, and morning headaches are all reasons to seek a sleep evaluation.

If your partner reports that breathing stops intermittently, the right next step is not only to purchase a side-sleeping pillow, but also to have a medical evaluation and, if necessary, a sleep study.

Why Sleeping on Your Side Helps with Obstructive Sleep Apnea

Obstructive sleep apnea occurs when the upper airway repeatedly narrows or closes during sleep. In some patients, the severity of the condition is highly dependent on body position: the apnea and hypopnea index is significantly higher when sleeping supine than in other positions. This condition is called position-dependent obstructive apnea.

A Cochrane review of eight randomized trials found that positional therapy aimed at reducing supine sleep does reduce the number of apnea episodes compared to no such therapy. However, continuous positive airway pressure reduced the apnea and hypopnea index more significantly. The reliability of some of the results was low, and the studies were mostly short. [12]

Therefore, the "side sleep" recommendation should not be used as a universal replacement for positive airway pressure or other prescribed therapy. The American Academy of Sleep Medicine considers positional therapy as an option for patients whose apnea is significantly reduced outside of the supine position, or as an adjunct to primary treatment. [13]

If a person is already being treated for apnea, changing position can be a useful part of therapy, but the decision is best based on the results of a sleep study, not just on the subjective feeling that "it's better to breathe on your side."

Which side is best to sleep on if you have heartburn?

In nocturnal gastroesophageal reflux, the left side is best studied.

The anatomical position of the stomach and the esophagogastric junction makes the left lateral position more favorable for reducing the reflux of acidic stomach contents into the esophagus. A 2023 systematic review found that the left lateral position was associated with shorter acid exposure time and faster esophageal acid clearance compared to the right lateral and supine positions. One randomized trial included in the review also found improvement in nocturnal symptoms with increased time sleeping on the left side. [14]

But body position is only part of the treatment. The American College of Gastroenterology recommends avoiding lying down immediately after eating for nighttime symptoms and, if possible, allowing several hours between late meals and bedtime; raising the head of the bed can also help with severe nocturnal reflux. [15]

Therefore, a person with reflux can use a simple principle: sleeping on the left side is preferable to the right or lying flat on the back, especially if symptoms occur at night. However, persistent or frequent heartburn still requires self-assessment as a condition, not just posture adjustments.

Right or left side: is there a universally healthier side?

For a healthy adult, there is no compelling reason to always choose only the left or only the right side.

The left side has a distinct advantage for nocturnal reflux. During late pregnancy, the side is preferable to the back, but modern obstetric recommendations do not require constant sleeping on the left side: the right side is also acceptable. [16]

Regarding the heart, there's a popular belief that sleeping on the left side is harmful because it "puts pressure on the heart." For healthy individuals, there's no high-quality data to support this universal rule. Studies do show small physiological changes in cardiovascular parameters with changes in body position, but this doesn't mean sleeping on the left side is harmful to the heart. In one study, sleeping on the left side of the body in healthy young adults did not worsen circulatory parameters, although it did slightly alter heart rate. [17]

A special situation is severe heart failure. Old observations show that some such patients spontaneously avoid the left side, especially with more pronounced cardiac enlargement and high filling pressure. This may be explained by a sensation of palpitations or shortness of breath, but such studies do not necessarily recommend that all heart patients sleep on the right side. [18]

If a person has difficulty breathing while lying down, has to sleep almost sitting up, or experiences severe shortness of breath in a specific position, it is no longer a question of choosing the “ideal side” - such symptoms require an assessment of the cause.

What's better for the lower back: the side or the back?

Both positions can be appropriate. The way the body is supported is of great importance.

When sleeping on your back, support under your knees is helpful: a slight bend in your legs reduces tension in the lumbar region and helps maintain a comfortable spinal curve. When sleeping on your side, a pillow between your knees helps reduce pelvic rotation relative to your spine. The Mayo Clinic recommends both approaches for people with back pain. [19]

A 2025 systematic review of six studies found that supine sleeping position was associated with a lower prevalence of low back pain, and that properly supported lateral sleeping position may also be beneficial. Stomach sleeping appeared less beneficial due to greater stress on the lumbar region. However, since the evidence is primarily observational, it is impossible to definitively determine whether posture was the cause of the differences in pain. [20]

This limitation is particularly important. A person with pain can change their usual posture on their own, so the study can identify a connection between pain and body position without determining which is the cause and which is the effect.

It's practical to focus on morning symptoms. If lower back pain develops after sleeping on your side, you can check the height of the pillow under your head, the position of your knees, and the support between your legs. If the pain intensifies after sleeping on your back, placing a pillow under your knees can help. If changing your position doesn't help, don't rely solely on "sleeping incorrectly" to blame the chronic pain.

What's more important for neck pain: posture or a pillow?

When it comes to neck pain, the position of the head relative to the body is often just as important as the choice between the side and the back.

On your side, the pillow should fill the space between your shoulder and your head. If it's too low, your head will tilt toward the mattress; if it's too high, it will tilt in the opposite direction. On your back, a lower support is usually needed because the distance between the back of your head and the mattress is smaller.

A systematic review and meta-analysis of pillow studies found that pillow shape and height can indeed influence cervical spine alignment and morning pain, although the benefits of specific materials were inconclusive. A more recent 2025 review also noted high heterogeneity in studies and the lack of conclusive superiority of one pillow type for all patients with chronic neck pain.[21]

Therefore, it is much more beneficial to strive for a neutral neck position than to look for a universal “orthopedic” pillow of a certain brand or to force yourself to sleep only on your back.

What if your shoulder hurts?

The evidence here is considerably weaker than it might seem. Pressure on the painful shoulder can subjectively increase discomfort, so someone with acute pain often naturally finds it more comfortable to sleep on the opposite side or on their back.

However, research does not allow us to definitively conclude that sleeping on one side alone causes shoulder problems. One cross-sectional study found a link between side of sleep and side of pain, but the authors explicitly stated that causality is unknown. Another study unexpectedly found opposite associations and also concluded that longitudinal studies are needed. [22]

Therefore, when it comes to shoulder pain, it's best to rely on tolerance. There's no point in lying on a sore shoulder for hours just to get the abstract benefit of sleeping on your side. If sleeping on your side is necessary, you can choose the opposite side and support the sore arm with a pillow in front of your body.

Is the back better for posture?

The phrase “the back is the only correct orthopedic posture” is too categorical.

It does allow for a fairly symmetrical distribution of body weight, and with the right pillow and knee support, it can be comfortable for the spine. However, a person sleeping on their side can also maintain a good spinal alignment if the mattress doesn't sag excessively and the head and pelvis are properly supported. [23]

The scientific literature on the relationship between sleep posture and long-term posture remains limited. An older review of spinal symptoms found insufficient studies to confidently identify a single posture as optimal. Even a more recent review from 2025 relies primarily on observational data. [24]

Therefore, an adult without a spinal disorder has no reason to retrain to sleep on their back just out of fear of “ruining their posture” by sleeping on their side.

Sleeping on your back during pregnancy

Late pregnancy is one important exception where the situation does change the recommendation.

The American College of Obstetricians and Gynecologists notes that sleeping on your back can put pressure on major blood vessels as the uterus enlarges. In its most recent expert opinion, revised in February 2026, the organization recommends avoiding sleeping on your back later in pregnancy and emphasizes that sleeping on either your left or right side is acceptable. If a woman wakes up on her back, there's no need to panic—just turn onto your side. [25]

A meta-analysis of data from five studies included 851 cases of late stillbirth and 2,257 pregnancies in the control group. Sleeping on the back after 28 weeks was associated with higher odds of late stillbirth compared with the left side; the right and left sides did not differ significantly. These were primarily observational data, so it is more accurate to speak of an association rather than proven direct causation. [26]

The practical conclusion is much simpler than the popular advice "avoid rolling over to the right throughout your pregnancy": after 28 weeks, it's wise to sleep on your side, whichever one feels most comfortable. There's no need to monitor your body all night or worry if you wake up on your back.

Should a pregnant woman sleep on her left side?

No, the current recommendation does not require the left side exclusively.

The American College of Obstetricians and Gynecologists explicitly states that both lateral positions are acceptable during pregnancy. A meta-analysis of individual data also found no significant difference in the risk of late stillbirth between the right and left lateral positions. [27]

The left side is sometimes subjectively more comfortable and is often recommended in popular materials due to circulatory issues, but this cannot be turned into a “right side is dangerous” rule.

Is it possible to retrain yourself to sleep on your side?

This is possible, but it should only be done if there is a cause, such as positional apnea, severe snoring, or reflux.

The simplest option is to provide mechanical support for the position using a pillow behind the back or a long body pillow. Studies of positional therapy for sleep apnea have used a variety of methods, including special belts and backpacks, pillows, and modern devices that vibrate when the patient rolls over onto their back. [28]

Retraining should not worsen sleep more than the underlying problem. If a person wakes up all night trying to maintain a firm side position, the effectiveness of this approach is questionable. If apnea is diagnosed, the results of positional therapy are best assessed objectively, not solely by snoring reduction.

What if I sleep on my back all my life and feel good?

Sleeping on your back in itself does not require correction.

If a person gets a good night's sleep, does not experience morning pain, the partner does not notice pauses in breathing or pronounced snoring, there is no nocturnal reflux or other special circumstances, there is no medical need to change the usual position.

This is an important point, because most comparisons of sleeping positions are conducted either in people with a specific condition or in small physiological studies. It's impossible to generalize the benefits of the side sleeping position for sleep apnea or reflux to every healthy adult and conclude that the back position is generally harmful.

And if you are more used to sleeping on your side?

Likewise, there is no need to switch to the back just because it is sometimes called more “orthopedic.”

The side position is the most common sleep position among adults in objective studies. This in itself does not prove its superiority, but it does show that this position is physiologically normal. [29]

If there is no shoulder or hip pain on the side, the neck is supported by a suitable pillow, and sleep is uninterrupted, there is no reason to consider the position incorrect.

Is there any point in sleeping on your stomach?

Compared to sleeping on your side or back, sleeping on your stomach is usually more challenging for the neck because the head must remain turned to the side for extended periods. The lumbar spine may also be in a state of significant extension.

A 2025 systematic review linked sleeping on the stomach with a greater likelihood of low back pain compared to the back and well-supported side positions, although the quality of this evidence base is limited by the observational study design.[30]

Therefore, when choosing between the side, back, and stomach, the stomach is often the least comfortable option for someone with morning neck or lower back pain. But even here, there's no need to forcefully retrain someone who has been sleeping comfortably on their stomach for years without symptoms.

How to choose the right pose for you

In practice, the solution can be reduced to several clinical situations.

Situation	Which position is usually preferred?	Why
No diseases and pain	Side or back - depending on comfort	There is no convincing evidence of a universal winner.
Loud snoring	More often the side	On the back, the upper airways are more easily narrowed
Positional obstructive sleep apnea	Usually side	Outside of the supine position, the number of respiratory events may decrease
Nocturnal reflux	Left side	Reduces acidic effects on the esophagus
Non-specific low back pain	Back with a pillow under the knees or a properly supported side	Both options are capable of reducing mechanical stress.
Pain in one shoulder	Opposite side or back as tolerated	Allows you to avoid putting direct pressure on the painful area
Late pregnancy	Right or left side	Sleeping on your back after 28 weeks is associated with adverse outcomes; both sides are acceptable
Heart failure with dyspnea when lying down	Individually, elevated position is often required	What's more important here is the disease itself, rather than the universal rule about right or left side.

The chart is not a substitute for diagnostics. Particularly in cases of apnea, severe reflux, heart failure, or chronic pain, postural modification is considered as part of the approach, not as a standalone treatment.

The mattress may be more important than the difference between side and back

If the surface is too soft, the pelvis or shoulders may sag excessively. If it's too hard, the pressure on protruding parts of the body increases, especially on the side.

A 2026 systematic review of 47 mattress studies most consistently supported moderately firm surfaces for adults with non-specific low back pain or morning stiffness. However, the authors emphasized significant heterogeneity in the data and the need to consider body type, age, and preferred sleep position. [31]

Therefore, a person who feels equally uncomfortable on both their side and back should evaluate not only their body position, but also the sleeping surface itself.

How to understand that a pose is not suitable for you

Minor movement and occasional changes in position during the night are normal. It's not the act of tossing and turning that should be cause for concern, but rather if sleep is systematically accompanied by morning pain, numbness in the arm, frequent awakenings, nighttime heartburn, or severe breathing difficulties.

If a specific symptom reproducibly improves after changing position, this is a useful practical clue. For example, the disappearance of heartburn on the left side corresponds to the known mechanism of reflux, while a decrease in loud snoring on the side may indicate position-dependent airway function.

But if the pain persists regardless of position, don't endlessly buy new pillows and blame sleep as the sole cause. Long-term neck, back, or shoulder pain has many possible causes and requires a separate evaluation.

When sleep position should not replace examination

If a person snores loudly and others notice repeated pauses in breathing, if they wake up choking, or if they remain noticeably sleepy during the day despite sufficient sleep, simply recommending "sleeping on their side" is not enough. The American Academy of Sleep Medicine emphasizes that treatment for obstructive sleep apnea should be based on an objectively established diagnosis. [32]

Also, you should not limit yourself to the left side if you experience frequent nighttime heartburn, difficulty swallowing, bleeding, unexplained weight loss, or persistent symptoms despite standard measures.

In cases of back pain, urgent evaluation is required not because of a specific posture, but rather if new, significant neurological impairments develop simultaneously, such as limb weakness or urinary control problems. In such cases, changing the bed position does not resolve the underlying problem.

Separately: for infants the rules are completely different

The advice on choosing a comfortable position between side and back applies to adults. Infants under one year old should be placed on their back for every nap. Side sleeping is not considered a safe alternative.

The American Academy of Pediatrics' current safe sleep guidelines recommend placing infants completely on their backs on a firm, flat surface. This even applies to most children with gastroesophageal reflux. Once a baby can roll over independently, they don't need to be placed on their backs all night, but they should be placed that way initially. [33]

This is an important exception: the advice for an adult with reflux to sleep on the left side cannot be extended to an infant.

What is often misunderstood

"It's better for everyone to sleep on their left side." No. The well-documented advantage of the left side exists primarily for nocturnal reflux. There is no evidence of a universal left-side advantage for healthy people. [34]

"Sleeping on your back is bad for your heart." There is no such general medical rule for healthy people. Sleeping position does change certain hemodynamic parameters, but these are physiological differences, not proof that sleeping on your back is harmful. [35]

"If you have back pain, you should definitely sleep on your back." No. Both a back with support under the knees and a properly positioned side can be comfortable. There is insufficient evidence to recommend a single position for all people with low back pain. [36]

"During pregnancy, only the left side is permitted." The current guidelines from the American College of Obstetricians and Gynecologists, revised in 2026, explicitly allow both the right and left sides. The main restriction concerns sleeping on the back later in pregnancy. [37]

"If you snore less on your side, your apnea is cured." No. Positional therapy does reduce events in appropriate patients, but continuous positive airway pressure has been more effective in reducing the apnea and hypopnea index in studies. [38]

"An orthopedic pillow will correct any poor posture." The evidence on pillows is mixed. Neck support is important, but a 2025 systematic review found no convincing superiority of one specific type of pillow for all patients with chronic neck pain. [39]

Frequently Asked Questions

What is better for a healthy person to sleep on - on the side or on the back?

Either way is fine. In the absence of sleep apnea, reflux, pregnancy, or pain, there is no convincing evidence that one of these two positions is significantly better for everyone's health.

What is the best pose for the spine?

There is no universal solution. Sleeping on your back with support under your knees and sleeping on your side with a pillow between your knees both help some people maintain a comfortable spinal alignment. [40]

Which side is better to sleep on?

For reflux, it's usually on the left side. During pregnancy, both sides are acceptable. For a healthy person without any special problems, you can choose the side that's most comfortable. [41]

Is it possible to sleep on your right side all night?

For a healthy adult, yes, if the position is comfortable and doesn't cause pain. There is no independent evidence of harm to the right side.

Is it true that the left side is better for the heart?

In healthy individuals, there is no convincing evidence of such a general benefit. In some patients with heart failure, on the contrary, the left side is subjectively more difficult to tolerate. [42]

What's best for snoring?

The side is often helpful. However, pronounced snoring with pauses in breathing requires ruling out obstructive sleep apnea. [43]

Is it okay to sleep on your back if you have sleep apnea?

For many patients, sleeping on their back worsens apnea. In position-dependent sleep apnea, a doctor may recommend avoiding this position, but this does not replace the prescribed primary treatment. [44]

What's best for heartburn?

For nocturnal reflux, the left side is best studied. Avoiding late meals and raising the head of the bed when necessary also helps. [45]

What's best for lower back pain?

You can try sleeping on your back with a pillow under your knees or on your side with a small pillow between your knees. Choose the option that reduces morning pain. [46]

Why does my shoulder hurt after sleeping on my side?

Prolonged pressure on the shoulder may worsen existing discomfort, but there is insufficient evidence that side sleeping alone is a common cause of shoulder pain.[47]

Is it possible to change sides in a dream?

Of course. Occasional changes in position are normal; adults typically change positions several times during the night. [48]

If you fell asleep on your side and woke up on your back, is that bad?

For a healthy person, no. The exception is when a doctor has specifically recommended avoiding the back, such as with confirmed positional apnea or late pregnancy.

Can a pregnant woman sleep on her right side?

Yes. Current recommendations allow both the right and left side. [49]

Do I need to buy a special pillow for side sleeping?

Not necessarily. The main goal is to fill the space between the head and the mattress so that the neck is not noticeably tilted. There is no evidence that one type of "orthopedic" pillow is universally superior. [50]

Key points from experts

Nancy Foldvary-Schaefer, MD, is a neurologist and sleep medicine specialist, professor of neurology, and a member of the Cleveland Clinic Sleep Disorders Center and its former director. She is board certified in sleep medicine, neurology, and clinical neurophysiology. [51]

In a Cleveland Clinic explanation, Foldvary-Schaefer points out that side sleeping is particularly beneficial for people with snoring and obstructive sleep apnea, as the supine position allows the tongue and soft palate to more easily shift backward, narrowing the airway. However, positional correction is most appropriate for certain patients and does not mean that every form of apnea can be treated with posture alone. [52]

Anne Srisuro is an obstetrician-gynecologist and a member of the American College of Obstetricians and Gynecologists. Her expert resource on common pregnancy questions was revised by the organization in February 2026. [53]

In this publication, the specialist explains that a pregnant woman does not need to lie exclusively on her left side: both sides are acceptable. The main recommendation is to avoid falling asleep on your back later in pregnancy; if a woman finds herself on her back upon waking, simply turning onto her side is sufficient. [54]

Philip Katz, MD, a gastroenterologist, professor of medicine, and director of the Motility Laboratories at Weill Cornell Medicine, specializes in esophageal diseases and gastroesophageal reflux disease. He is the lead author of the current American College of Gastroenterology guidelines for the diagnosis and treatment of reflux disease. [55]

A guideline prepared by Katz et al. for patients with nocturnal reflux discusses measures to reduce nocturnal reflux of gastric contents, including elevating the head of the bed and avoiding eating immediately before bedtime. An additional systematic review of studies on body positioning suggests that the left side is superior to the right side and back in reducing nocturnal acid exposure. [56]

Main

For a healthy adult, it's impossible to say that the side is always better than the back, or the back is always better than the side. Both positions are physiologically normal, and in the absence of specific problems, it's wiser to choose the one that promotes a more restful sleep and prevents pain in the morning.

Medical exceptions are much more important than the overall rating. For snoring and positional obstructive apnea, the side is often preferred; for nocturnal reflux, the left side is preferred; after 28 weeks of pregnancy, it is reasonable to sleep on the right or left side; for non-specific lower back pain, either a properly supported side or the back with a pillow under the knees is suitable. [57]

Therefore, instead of trying to find a single "healthiest" position, it's more helpful to pay attention to specific nighttime symptoms. If a change in position reduces heartburn or snoring, that's helpful. If there are pauses in breathing, severe daytime sleepiness, persistent pain, or severe shortness of breath when lying down, posture adjustments alone are insufficient and the underlying cause needs to be assessed.