Hot Feet
April 15, 2012 7:24 PM   Subscribe

Usually my feet are chilly, and I wear socks lounging around on my bed. But I can always tell when I'm drowsy and ready to nod off, because my feet feel suddenly unbearably warm, and I have to rip my socks off so I can fall asleep. I've always wondered why--any thoughts?

A bit of background: I've experienced this for as long as I can remember. I have low blood pressure and my peripheral circulation's not the best. I can lie down for prolonged periods of time--say, reading in bed--and my feet feel chilly for as long as I'm alert. It's only as I start to fall asleep that they get hot. They also turn pink, while generally they're pale and the toenails look a bit blue. It's not a major problem for me--I just take off my socks. But I really would like to have an explanation.
posted by DrMew to Health & Fitness (11 answers total) 5 users marked this as a favorite
I have to wear socks or slippers at all times too, and I also have low blood pressure (not unhealthily so, just low end of "normal"). And every evening without fail, there comes a point where I have to throw my socks off because my feet suddenly feel claustrophobic.

I don't know why it happens, but you're not alone!
posted by katypickle at 8:15 PM on April 15, 2012 [2 favorites]

My kids get hot as they are getting sleepy too. I have no idea why, though.
posted by dawkins_7 at 8:33 PM on April 15, 2012

Have you considered maybe you've got the causation backwards? I've always seen this as "I can't sleep when my feet are cold." Indeed, for me the way to get to a point where I can sleep entirely revolves around making sure my feet are warm enough. Once they are, I drop right off. So where other people might count sheep, I'm putting my feet against a hot water bottle.

I think the blue feet to red feet transition sounds like Raynaud's phenomenon.
posted by troublesome at 8:51 PM on April 15, 2012 [2 favorites]

Wow, i thought i was the only sock-removing weirdo. My theory: I have night sweats, and when I get tired my brain says "okay, we're going to get toasty here so let's remove a layer in preparation."
posted by desjardins at 9:07 PM on April 15, 2012

I do the exact same things. I kick my socks off right before I fall asleep. Whenever I change the sheets I find all kinds of missing socks...
posted by fyrebelley at 9:43 PM on April 15, 2012 [5 favorites]

Not sure why your feet are normally so cold or why going to bed warms them up, but the sudden temperature change making you sleepy tracks with a weird cure for insomnia which I first heard about as a kid.

Basically the idea is that if you wear a wet sock to bed, it will knock you out by causing a sudden rush of blood from the head to the extremities as your body works to warm up the wet foot.
posted by the latin mouse at 10:18 PM on April 15, 2012

Your body temperature drops as you go to sleep at night, and one way the body gets rid of its heat is dilation of the blood vessels in your extremities. Blood rushes into your feet, they feel hot, heat radiates outward, your temp drops, you go to sleep.

Here is a page about body temperature variation throughout the day.

This is for children, but talks about temperature regulation and extremities and sleep.
posted by purpleclover at 10:21 PM on April 15, 2012 [11 favorites]

My whole body "changes polarity" in the night -- it's really hard for me to get warm enough at start of night (cuddle up against warm spouse, use hot water bottle, etc.), but by morning *I'm* the radiator in the bed and I've kicked off a layer of blankets. Don't know what it's all about, but clearly homeostasis means something else when you're asleep! :)
posted by acm at 6:25 AM on April 16, 2012 [1 favorite]

No, that makes sense. Look at the chart in the first link I posted: Your core body temperature peaks at about 7 p.m. and bottoms out at about 4:30 a.m. So for most of the night your body is trying to throw heat off by sending blood to the outer areas of the body -- that means your skin gets hot, and it's not comfortable to be trapping that heat under blankets. This process is just starting when you're going to sleep, which is why you feel cold still. (Warm hands and feet are the very beginning of the temp drop.)
posted by purpleclover at 7:33 AM on April 16, 2012

Response by poster: The diurnal cycle theory is quite sensible. However, I'll get a case of hot feet if I get drowsy for a midday nap, and I'm never troubled by my hands feeling hot (I know--they're not in gloves--but I tuck them behind my head as I'm drifting off to sleep). So I'm still left with something of a mystery.
posted by DrMew at 2:24 PM on April 16, 2012

Here's another chart that shows basal body temperature variation over the course of a day. Both this chart and the first one I linked to have what appear to be a mid-afternoon dip in temperature. I'd hazard a guess that this corresponds to that mid-afternoon drowsiness, and again, your body trying to throw off heat.

As for the hands business -- are your hands often cold? Considering your circulation issues, I'd imagine that what you're really noticing is the difference between how your feet normally feel (cold) and how they feel when your temperature is dropping and they pink up and get a bunch of bloodflow. You don't go through the same extremes with your hands? Again, that's just a guess. My feet are often colder than my hands, perhaps the same is true of you?
posted by purpleclover at 4:15 PM on April 16, 2012

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