Leg cramps are a common condition that can ruin a good night's sleep. Jane Collins explains why they occur and the steps you can take to stop them happening.
🕒 6 min read
Cramps may not be unusual or life-threatening, but they are unpleasant and painful and can significantly disrupt your sleep. Interrupted sleep then not only leaves you feeling exhausted and irritable but, if it persists over time, can raise your risk of many disorders and chronic conditions, including heart disease and stroke, obesity and dementia.
In short, sleep is a biological necessity, and we all need it to help our body repair itself.
Everything from your brain to your blood vessels and your immune system can become impaired if you don't get enough good-quality sleep. If night-time leg cramps are getting in the way of a good night's rest, here's what could be causing them and how you can get them under control.
What are leg cramps, and what causes them?
A leg cramp, as many of us know, is the painful feeling when a muscle – generally in the calves or feet – involuntarily clenches and contracts. These cramps tend to subside within minutes, but they can be deeply intense, shockingly painful and, unsurprisingly, the discomfort is enough to wake you up.
Experts don't know exactly what causes cramps at night, but common reasons include some medications (such as diuretics), pregnancy, dehydration, and exercise, and they are known to be more common in women and older adults.
Other factors that may contribute to leg cramps include:
Prolonged standing. Research shows that people who stand for prolonged periods of time at work are more susceptible to night-time leg cramps.
Exercising without warming up. This can lead to muscle cramps. Similarly, if you don't stretch your muscles after prolonged exercise lactic acid can build up, causing cramping.
A sedentary lifestyle. Your muscles need to be stretched regularly to function efficiently. Sitting for long periods can make them more susceptible to cramping.
Shortened tendons. The tendons that connect muscles and bones shorten over time, leading to a greater chance of nocturnal leg cramps as you age.
Sitting with your legs crossed. Doing this for lengthy periods can, over time, lead to a shortening of your calf muscles that could potentially lead to cramping.
A lack of certain nutrients. Cramps are linked to low levels of essential minerals: notably magnesium, but also potassium, calcium and sodium – collectively known as electrolytes. These minerals are essential for your body to function optimally.
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How to reduce your risk of leg cramps while you sleep
Stay hydrated
Fluids help your muscles to relax and contract, so to allow for effective muscle function you need enough liquid each day.
Try to drink enough fluids like water, herbal teas and/or reduced-sugar squash consistently throughout the day. Aim to cut down on caffeine, which is known to have a stimulant activity that can induce muscle contractions.
However, avoid drinking too much of anything too close to your bedtime, as this may cause you to wake up needing the toilet and disrupt your sleep in a different way.
Magnesium – the mineral for muscle health
Magnesium has muscle-relaxing and sleep-enhancing benefits, and is vital for strong healthy muscles. Along with calcium, it's also involved in muscle contraction, allowing them to efficiently lengthen and shorten.
However, modern life can get in the way of getting enough magnesium – a diet with too much caffeine, alcohol, fizzy drinks, ultra-processed foods and sugar can lead to depleted levels, and stress can also hammer your stores of this mineral.
On top of that, your body's ability to metabolise magnesium can decrease with age, and typically we only absorb around half the magnesium present in food sources (such as nuts and seeds, dried fruit, fish, dark green leafy vegetables and pulses).
Significantly, a magnesium deficiency is frequently linked to muscle weakness and increased cramping, and research has shown that supplementing with this mineral is highly effective at reducing night-time leg cramps in pregnant women, although it has yet to be conclusively established whether it is effective for other groups.
Magnesium for sleep
A study on older adults also shows that magnesium supplementation helped those in the trial to fall asleep faster and reduced the likelihood of them waking up earlier than intended – so supplements should help those who struggle to sleep and are being woken up by problems caused by low magnesium levels, such as nocturnal leg cramps.
Look for supplements containing magnesium citrate and malate, the two more highly absorbable forms of the mineral, and to achieve optimum levels aim to get the recommended daily intake of 375mg.
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Get more electrolytes
Research reveals that drinks containing electrolytes – such as potassium, calcium and magnesium – appear to help prevent muscle cramps. These exist as sports drinks or dissolvable tablets. Eating a diet rich in foods containing electrolytes such as bananas, sweet potatoes, avocados, pulses, melon and milk should also help to prevent any imbalances that could trigger cramps.
Stretch your legs
Performing a few gentle stretches of your calves regularly throughout the day and before getting into bed appears to reduce the frequency and severity of night-time leg cramps. The HSE website has a stretching guide. Aim to hold the stretches for a few seconds each.
Check your bedding
Having very heavy or tightly tucked-in bedding can have the effect of pushing your feet downward or constricting your calf muscle while you sleep, which can induce cramping. Keep your bedding loose and untucked and avoid piling your bed with heavy blankets
Wear supportive footwear
Badly fitting shoes or ones that offer little support can cause problems in the muscles in your feet and calves, particularly if you have flat feet.
Choose comfortable shoes that actively support your feet, such as well-cushioned trainers and walking boots, and try to avoid ones like flip-flops (which cause your toes to grip and bunch up to keep them on, which can compromise the muscles in your calves and feet), high-heeled shoes (which tip your weight forwards and shorten your calf muscles) or ballet pumps, which tend to lack any internal support or padding.
If you are woken by a painful leg cramp:
- Massage it. Most of us do this instinctively to help relax the muscle and minimise the pain. Use one or both hands to gently massage the affected area and loosen up the muscle and boost circulation.
- Stretch it out. If the pain is in your calf, straighten your leg out in front of you. Flex your foot so that your toes are pointing towards you.
- Heel walk. Walking on your heels should engage the muscles opposite your calf, allowing the calf to relax and helping the pain to subside.
- Warm it. Heat can help to relax tightened muscles. Holding a hot towel or hot water bottle against the affected area should help. A heat pad can also be soothing.
- Take a painkiller. If your leg remains sore and uncomfortable after the cramping episode, take a non-steroidal anti-inflammatory drug (NSAID) such as ibuprofen to help ease the discomfort.
When to be worried about night-time leg cramps
Can leg cramps signify something more sinister? Rarely, but they are associated with, and can be a side effect of, osteoarthritis, diabetes, Deep Vein Thrombosis (DVT), neurodegenerative conditions like Parkinson's disease and structural issues like flat feet.
If your leg cramps are becoming worse, more frequent, last longer than 10 minutes and are taking their toll on your sleep, see your GP, who can assess your situation fully.
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