why do my legs bend when i sleep?
Sleep Positions

Why Do I Sleep with One Leg Bent Up?

(Last Updated On: December 30, 2022)

We all have a preferred sleeping position, and it rarely involves lying stock still and pencil-straight all night. Whether you consciously choose to do so or unwittingly move in your sleep, you may curl and bend one leg overnight.

Bending the leg can adjust the body temperature, either retaining warmth or allowing you to hang a foot out of bed to cool off. Bending the leg can also assist with weight distribution in a shared bed or enable a very tall person to remain under the covers.

Sometimes, there’s a medical explanation for bending one leg in your sleep. If you adopt this position without realizing it, you may have periodic limb movement disorder, which is similar to restless leg syndrome. This can be managed with lifestyle changes or medication.

There can be consequences to sleeping with one leg bent. You may take up more of a bed than you mean to, disturbing a partner’s sleep, and the position can apply pressure to the pelvis and lower back. Restricted blood flow can also lead to numb feet upon waking.

Try placing a pillow between your knees when you go to bed. This should prevent you from subconsciously bending one leg while you sleep and could lead to improved spinal alignment.

Why Do My Legs Bend When I Sleep?

Some of us consciously choose to sleep with one leg curled up, especially tall people.

A standard double bed will be 6 feet and 3 inches long, though some of this space may be lost to a headboard, and a mattress could be an inch or two shorter.

So, anybody over 6 feet tall may find their feet hanging out of the bottom of the bed if they attempt to lie straight. Curling the leg before sleeping is a way to keep the entire body under the blankets.

You may choose to bend your legs in an attempt to retain a sleeping position throughout the night. If you’re prone to tossing and turning, bending your leg will make this more difficult. Assuming this position while on your stomach may hold you into place.

For many people, bending the leg is an involuntary action that arises during sleep, but there are three explanations for why it happens:

Weight Distribution

You may feel compelled to lift and bend your legs at night to manage weight distribution in a bed. This is especially likely if you share your bed with a heavier partner, as their weight may create a divot in the mattress that forces you to move to one side.

Bending a leg can also reduce the pressure of your weight in the bed, especially if you lie on your back in the supine position. This can be more comfortable if you have a back issue, but bending one leg can worsen this problem in the longer term.

Some people adopt the fetal position when sleeping to minimize pressure on any single body part. You’ll bend both legs in this position, which is preferable to just one. This position can exert pressure on the spine and neck, so consider adjusting periodically.

Temperature Regulation

Maintaining an appropriate body temperature is a vital component of restful sleep.

Frontiers in Neuroscience explains how our core body temperature drops as we drift further into sleep, particularly when entering the critical REM sleep phase.

While reducing body temperature will help you sleep, feeling cold can keep us awake if we’re uncomfortable. Bending one or both legs can help the body curl up and retain the warmth provided by the blankets.

The opposite can also be true. If you feel too hot and sleep at the edge of a bed, you may bend your knee to hang one leg out of the side of the covers. Body heat is lost through the extremities at night, including the feet, which could help cool you off and keep you asleep.

is it bad to sleep with one leg bent?

Periodic Limb Movement Disorder (PLMD)

There could be a medical explanation for your tendency to bend your leg at night.

The first is restless leg syndrome, which compels somebody to regularly fidget with the legs. People with restless leg syndrome are aware of their actions.

If you only bend your legs during the subconscious of sleep, the concern is likelier to be periodic limb movement disorder (PLMD). Sleep Medicine Reviews confirms that up to 11% of people live with PLMD.

Anybody with restless leg syndrome is more likely to live with PLMD, which manifests while we sleep. This condition is most common in those aged 60 or over and left-handed people.

Other common causes of PLMD include:

  • Iron deficiency.
  • Diabetes or pre-diabetes and associated nerve damage to the legs and feet.
  • Side effects of certain medications, especially antidepressants.

PLMD can be treated with medication, supplements, and lifestyle changes.

Is it Bad to Sleep with One Leg Bent?

Sleeping with one leg bent up isn’t ideal if you share a bed because it causes you to take up more space and will potentially knee a partner in the back, disturbing their rest.

Even if you sleep alone, you may experience physical discomfort in the morning after adopting this position overnight. This raises the question of what happens when you sleep with your legs bent and why it is sub-optimal for physical health.

Pressure on the Pelvis

Some people bend their legs and knees to relieve pressure on the lower back while sleeping. If you only bend one leg, this will lead to uneven weight distribution, and more pressure will be placed on one side of the pelvis than on the other.

Initially, this can lead to soreness and pain in the hips when you first wake up. This may pass with a stretch and a gentle massage, but the wear and tear will build up over weeks, months, and years of sleeping this way.

Eventually, this lack of balance can cause misalignment in your spine. Your posture will suffer, and back problems – including significant pain – will become more pronounced. If you must bend a leg while you sleep, elevate both.

Numbness in The Feet

Bending one knee will restrict the blood flow to the lower leg while you sleep. If you adopt this position occasionally, that doesn’t need to be a significant concern. Over time, it can lead to peripheral arterial disease or varicose veins.

Limited blood flow can also cause numbness in the feet when you wake, more commonly referred to as “pins and needles.” It won’t take long for the feeling to return to your foot, but it can be dangerous to attempt to walk until the numbness passes.

If you have one numb foot and one that boasts feeling, you’ll likely find yourself unbalanced. Couple this with the grogginess associated with waking from a deep sleep, and you risk slipping and falling, potentially leading to injury.

How to Stop Bending Your Leg in Your Sleep

You may eventually suffer consequences if you regularly sleep with one leg bent. Thankfully, there are some techniques you can adopt to train yourself to adopt a different posture while sleeping.

The simplest approach is to sleep with a pillow between your legs. This can be done in any sleeping position, whether you prefer to lie supine, prone, or on your side. Sleeping on your left side, knees separated by a pillow, will aid digestion and a restful night’s sleep.

Try exercising your legs during the day, and cut out caffeine and alcohol before sleep. These lifestyle remedies for restless leg syndrome will help you maintain a single position overnight with less fidgeting.

Sleeping with one leg bent may feel initially comfortable, but it’s not always a sustainable position for restful sleep and good posture. If this position is causing you concern upon waking, identify why you adopt such a pose and work to adjust to your sleeping position.