Your new mantra: Heat your feet to get better sleep. Photo / 123rf
I struggle with getting good sleep. What can I do about it?
Try heating up your feet at night with one of these methods:
Warming the extremities before bed has been shown to help people fall asleep more quickly. It does so as well as many over-the-counter sleep aids.
“It’s a natural sleep medication,” said William Wisden, a professor at Imperial College London who studies how nerve cells signal sleep.
Many animals – humans included – “nest” in preparation for sleep to create a warm microenvironment surrounding their bodies, whether by curling up, wrapping themselves in bedding or donning fuzzy socks. “Having warm skin, especially hands and feet, induces drowsiness,” Wisden said.
Studies have found that warming the skin before bed not only makes you “feel” tired but also creates changes in your brain activity corresponding to longer periods of deep sleep.
Decades of studies have confirmed this effect. An oft-cited 1999 study published in Nature found that the degree of dilation of the blood vessels in the feet, such as occurs when we wear warm socks, was the best predictor of how quickly people would fall asleep – more so than melatonin levels or even how “sleepy” the subjects felt.
And a randomised controlled trial of 46 men over the age of 60 found that warming the feet in the bath one hour before bedtime every night for six weeks resulted in improvements in how quickly the men fell asleep and how long they slept. These findings have been supported by multiple additional studies in older adults.
If you do opt for a full-on warm bath or shower, a 2019 meta-analysis found that doing so even for as little as 10 minutes one or two hours before bed helped people fall asleep about nine minutes quicker and boosted sleep efficiency – that is, the time of objectively measured sleep compared to time spent in bed.
For perspective, melatonin supplements help people fall asleep about seven minutes quicker, and zolpidem, sold as Ambien, helps people fall asleep around 10 to 20 minutes quicker. So, all things considered, falling asleep nine minutes quicker is pretty good for something as simple as warm water.
Wisden cautions that warming the extremities is only impactful when implemented later at night, when your own circadian rhythm is preparing for sleep. People who take warm baths earlier in the day – say at 4pm – don’t experience this benefit.
Some scientists think the reason heating up your feet works well is not because you become so toasty, but paradoxically, because by dilating the blood vessels in the skin, you’re ultimately helping your core cool.
That’s why a warm room won’t necessarily help. It’s the combination of warming your skin before bed and sleeping in cooler ambient temperatures that researchers have found is most helpful for staying asleep.
The body’s core temperature drops by around 1.1 to 1.7 degrees Celsius as we fall asleep, and it needs to stay that way to maintain a deep sleep. The trouble is, of course, we usually set our thermostats once for the night and don’t change it while we sleep.
For that reason, it’s very common, Wisden said, for people to wear socks to sleep, only to wake up in the middle of the night and pull them off because they feel overheated. But being too cold can arouse you from sleep as well – and whether you feel hot or cold during sleep depends on a combination of factors including your pyjamas, bedding and ambient bedroom temperature.
Therefore, layers are helpful, Wisden advised, because they allow you to adjust your microenvironment as your body’s thermal needs shift throughout the night. Whether it’s through subconsciously kicking off your comforter as you roll over, or throwing your socks unceremoniously on the floor, layers keep you nimble and adaptable.
If you haven’t had at least one argument with a flatmate, romantic partner or ex-best friend about the optimal room temperature at night, you’ve missed out on a formative human interaction. People feel very, very strongly about this topic.
So when I tell people that, according to the National Sleep Foundation, experts often recommend an ambient room temperature of 15C to 19C at night – well, you can imagine the stares of disbelief.
I know people who would embrace such a chilly room, but others would find that range closer to torture than comfort. That’s because there’s a normal amount of variability in what temperatures each person finds comfortable during the night. It’s well described that women tend to prefer sleeping in slightly warmer conditions than men.
There’s a surprising way you can inadvertently cancel out the benefits of skin warming before bed: by taking nonsteroidal anti-inflammatory medications, or NSAIDs, like ibuprofen or aspirin.
Many people grasp for these medications at the end of the day to alleviate muscle aches or headaches. But researchers found that NSAIDs, which cause small blood vessels to constrict throughout our bodies, counteract the effect of warm baths and socks. Even if you took the warm bath out of the equation, smaller studies have found that NSAIDs can disrupt sleep cycles in general, which could also be due to their impact on melatonin production.
Check with your doctor for pain management alternatives. It may be worth considering acetaminophen for pain relief before bed instead. A clinical trial found that people who took acetaminophen do not experience the same disruptions to sleep as NSAID users.