why do I curl up when I sleep?
Sleep Positions

Why Do Humans Curl Up When They Sleep? (Foetal Position)

Last Updated on February 12, 2024 by Louise Carter

The fetal position, which involves sleeping on the side with the knees curled, is among the most popular, especially among senior women.

While scientists haven’t settled on an explanation, it’s believed that this posture promotes safety and security, especially among people who feel shy or vulnerable during sleep.

Sleeping in the fetal position promotes natural spinal alignment. This reduces the likelihood of snoring and sleep apnea, supports coronary health, and eases heartburn or acid reflux symptoms.

Adopting the fetal position can also keep the body warm overnight because less skin is exposed. Side sleepers, including those who assume the fetal position, have less risk of cognitive decline later in life.

Avoid balling yourself up too tightly if you regularly sleep in the fetal position because it can exert pressure on the diaphragm and cause respiratory distress.

Alternate between sleeping on your left and right sides to minimize shoulder pain and skin wrinkles.

What Is The Fetal Position?

This sleeping position takes its name from the posture of a human fetus when gestating within the womb. The fetal position involves lying on your side and lifting your knees to level with your chest.

Some people who assume the fetal position wrap their arms around the knees, while others place at least one arm under a pillow to elevate and support the head.

foetal position sleep meaning

Why Do I Curl Up When I Sleep?

There are three core sleeping positions: lying on your back (supine), front (prone), or side. The fetal position is an extension of sleeping on your side.

Sleep experts and psychologists have studied potential reasons why some people prefer to adopt the fetal position in bed, with various theories abounding.

As mentioned, the most commonly held belief is that the fetal position during sleep can be linked to feelings of shyness and sensitivity. This position is believed to offer protection and shielding from the outside world, especially when also covered by blankets.

Another belief is that sleeping in the fetal position brings a sense of security and reduced vulnerability, connected to feelings of being back in the womb.

This may be the case if you feel more comfortable sleeping beside a wall or another physical batter.

Is The Fetal Position Good for Sleep?

There are advantages to adopting the fetal position when you sleep, especially if you’re pregnant, snore, struggle with back pain or limited mobility, or have regular heartburn and acid reflux.

Here are the most common fetal position benefits:

Reduced Snoring

The journal Sleep explains that sleeping on the side minimizes the risk of snoring. Leaning on your side reduces blockages to your airways, reducing the likelihood of loud snoring.

Sleeping with a partner can be challenging in the fetal position, especially if you prefer to cuddle at night.

However, this posture can help everybody have an undisturbed evening of rest and negate the need to wake somebody who is keeping you up with their snoring.

Remedy for Heartburn

Heartburn and acid reflux cause discomfort when lying down, preventing restful sleep. While eating several hours before bed allows time for digestion, that may not be possible with a busy schedule.

The American Journal of Gastroenterology explains that digestive acids in the esophagus clear faster and easier by sleeping on your side, especially on your left-hand side.

If you struggle in the fetal position, add more pillows and place at least one hand underneath. The more elevated your head and neck are during sleep, the fewer adverse symptoms you’ll experience.

Heart Health

Sleeping in the fetal position can improve general cardiac performance, especially in pregnant women.

MedLine Plus explains how sleeping on your left-hand side with the knees bent makes it easier for the heart to pump blood around the body, as it prevents a fetus from applying pressure to veins.

Sleeping on the left side improves blood flow around the major organs, including the liver and kidneys, due to greater heart flexibility that encourages active, regular pumping.

Spinal Alignment

If you’re prone to back pain, consider adopting the fetal position while sleeping. This posture encourages a natural spinal alignment, reducing pressure on your lower back.

The fetal position will also relieve the discomfort associated with compacted vertebrae because it opens up your spine more and leaves greater space between each disc.

Be mindful of how the rest of your body feels upon waking when you sleep in the fetal position.

While adopting this position can reduce pressure on your back, that weight must be reapplied elsewhere. Ensure you’re not harming your hips or knees.

If you experience joint soreness after spending the night in the fetal position, pair this posture with strategically placed cushions to ease weight-bearing on other body parts.

Fewer Neural Disorders

Sleeping at night is vital for a healthy mind. According to the Journal of Molecular Medicine, the brain undergoes a nightly ‘drainage of waste’ while sleeping, with anything unnecessary flushed into the bloodstream by cerebrospinal fluid during slow-wave sleep.

This process removes anything deemed unnecessary by the brain, allowing it to focus on retaining important memories, reducing the risk of cognitive disorders like Alzheimer’s disease later in life.

ScienceDaily claims that side-sleepers enjoy a more efficient ‘brain drain’ and waste removal than those who adopt prone or supine positions.

Temperature Regulation

While slightly lower body and ambient temperatures encourage us to fall asleep faster, growing cold at night will disturb sleep. The fetal position can help retain body heat at an optimal level.

Cool your bedroom with a fan or by opening a window before getting into bed, and consider taking a bath or shower to reduce your body temperature.

Curling up reduces exposure to cool air. This means you’re likelier to maintain a consistent temperature throughout the night and not be woken up shivering and uncomfortable.

Is Sleeping Curled Up Bad for You?

Not everybody will be comfortable sleeping in the fetal position, and this posture can cause health and safety issues if held for too long.

Even though the fetal position is celebrated for maintaining the spine’s natural alignment, it can place pressure on the back if held for hours.

Here are some other concerns connected to sleeping in the fetal position:

Pressure on the Shoulders

Sleeping on the side exerts additional pressure on the shoulders. This risk is increasingly prevalent in the fetal position, as one’s weight naturally shifts toward the upper half of one’s body.

The Journal of Manipulative and Physiological Therapeutics surveyed 83 people with shoulder pain and found that 67% slept on one side, which was invariably the site of the discomfort upon waking.

When in the fetal position, regularly alternate between sleeping on your left and right sides. Make this change at night, but if that isn’t an option, spend one night on your left and the next on your right.

Elevate your head by getting firmer memory foam pillows or stacking more pillows and cushions in your bed. This alleviates some of the pressure on the shoulder muscles.

is the foetal position good for sleep?

Skin Damage

One side of your face will be pushed into a pillow, causing ‘sleep lines’ in the skin. Regularly adopting this posture may change your face shape over time.

The Journal of Cosmetic and Laser Therapy recommends the supine sleeping position to avoid skin wrinkles, but this position doesn’t accommodate the psychology associated with the fetal position.

As with reducing shoulder pain, alternating between left- and right-side sleeping can be beneficial. Specialist anti-aging pillows prevent tugging at the facial skin due to smooth and gentle materials.

Restricted Breathing

Don’t ball yourself up too tightly when assuming the fetal position in bed. If you place too much pressure on the diaphragm, you may struggle to breathe due to a restricted lung capacity.

If so, place a soft cushion between your knees and chest when you climb into bed. This will create a barrier that enables appropriate breathing without causing discomfort.

Try to avoid hugging your knees. If you release your arms around your legs, you won’t inadvertently draw your knees closer to your chest as the night unfolds.

How To Stop Curling Up While Sleeping

If you discover that the drawbacks of sleeping in the fetal position outweigh the benefits, you can train yourself out of assuming this posture at night. Techniques include:

  • Place pillows between your upper chest and knees, creating a barrier when you curl.
  • Get a new mattress that offers lumbar support, reducing the need to curl up to relieve back pain.
  • Redecorate your bedroom with relaxing colors that make you feel safe and secure before sleeping.
  • Perform stretches before bed so your muscles feel loose and relaxed, which will instinctively encourage you to keep your legs straight.
  • Use a hot water bottle to minimize the need to curl up for temperature regulation.

While many people, especially older women, find the fetal position beneficial for a good night’s sleep, this isn’t the case for everybody. Always pay attention to how refreshed your body and mind feel.