Cold Feet

Many of you are familiar with the horror I describe in this week’s post.  If not, let me set the stage:

The scene is a dark bedchamber where we hear only muted breathing and the rhythmic tick of a grandfather clock.  A man lies peacefully under the covers, dreaming of far away places on a cold winter’s night.  Slowly, silently, something inches its way under the sheets, stalking its unsuspecting victim (cue the unsettling melody of violins in a minor key).  Closer and closer the form comes, seeking its prey like a feral cat slinking toward a slumbering rat.  All at once it strikes, chilled digits pressed insistently against the warm thighs of the shrieking victim.  The cold-footed spouse has stuck again.  A dog howls in the distance.

The horror!  But as bad as it is for the warm-blooded spouse to have their legs serve as a heating pad for frozen toes, the person whose feet never warm up at night is the real victim in this drama.  Having ice cubes for toes is a miserable way to try falling asleep at nights—can you really blame them for seeking warmer spots under the covers?

I’ve been asked many times what causes cold feet.  Most patients believe they have a blockage in the arteries or some other serious problem.  They’ve been led to that conclusion by various web sites that warn them of the grave dangers that lurk within the bodies of those who suffer with this problem: hypothyroidism, peripheral arterial disease, congestive heart failure, anemia.  Most of the people who come to me with this complaint believe they have “poor circulation.”

While it is true that these illnesses can produce cold limbs, the vast majority of people with cold feet are absolutely healthy with no obstruction of arteries or imbalance of hormones.  They simply suffer from a syndrome termed primary vascular dysregulation or vasospastic syndrome (it turns out that this problem is so common in Japan that they have a name for it: hi-e-sho, meaning “cold syndrome”).

In order to best explain vasospastic syndrome (VS), let me first start with a description of normal vascular regulation.  Blood arrives to the hands and feet via large arteries and smaller arterioles.  These vessels are not merely pipes but rather functional, dynamic structures that are wrapped with small involuntary muscle fibers and can expand and contract based on the needs of the body.  The actions of vasoconstriction (contraction) and vasodilation (expansion) are not under your conscious control—a variety of nerve and hormonal stimuli regulate these functions on a second-to-second basis.

In most people, contraction and expansion of the arterioles in the hands and feet are heavily influenced by body temperature.  If you’re too hot the small vessels in the extremities dilate in order to shunt warm blood to where its heat can be dissipated.  When you’re cold, the opposite happens and you conserve warmth by shielding the bulk of your blood volume from your chilled skin. In a way, this is proof of the old adage about cold hands implying a warm heart: you shunt blood away from the periphery to keep the heat inside.

When this system is taken to the extreme, as in the case of people who suffer from Raynaud’s phenomenon, the arterioles constrict to such a degree that all blood flow gets cut off and the digits become cold, white, and painful.  Those afflicted with Raynaud’s have to be very careful to avoid stimuli (such as exposure to cold and cigarette use) that can trigger this reflex.

The cold-footed population has a similar, yet not so severe, problem in that the arterioles in the feet tend to overreact in their attempt to conserve core body heat. In and of itself this is a bothersome enough problem, but, as researchers have found, the syndrome of cold feet tends to be coupled with another nighttime problem: insomnia.

The process of falling asleep involves a series of temperature changes in the body.  Researchers have found that your core body temperature drops just prior to drifting into fitful sleep and that your body cools by shunting blood to the arms and legs in order to dissipate heat.  As described in the venerable journal Nature, “the degree of dilation of blood vessels in the skin of the hands and feet, which increases heat loss at these extremities, is the best physiological predictor for the rapid onset of sleep.”

Sufferers of VS are unable to effectively accomplish the task of heat dispersion.  Instead of cooling the body by warming the extremities they constrict the arterioles in the feet in an attempt to conserve body temperature.  The net effect is that most people with cold feet in bed also have more trouble falling asleep.

But this isn’t all they suffer from.  Studies of large populations of VS patients show that they’re also more likely to develop glaucoma, migraine headaches, tinnitus, and even stroke and heart attack.  This syndrome tends to affect women more than men, is more common among younger rather than older individuals, and is most prominent in people who are of thin body stature.  It’s estimated that about 30% of the population suffers from VS at some point in their lives.

What do you do if you have VS?  Well, for starters, it’s highly unlikely that you have a blockage in the arteries of your legs or some other illness.  People with true peripheral arterial disease often develop cramping in the calfs, thighs and buttocks while walking.  Patients with anemia and hypothyroidism are frequently beset by other constitutional symptoms.  In contrast, most VS sufferers are in excellent health and need to undergo no costly diagnostic testing.

The key, of course, is warming the feet at bedtime, and how you do this is your business.  Some experts recommend a warm bath prior to bed while others suggest a hot water bottle or heating blanket at the foot of the bed.  There are online outlets that sell electric socks and booties designed specifically to warm the feet of those with VS.

I’ve suffered from VS for most of my life.  When I crawl into bed my feet are about the same temperature as the North Atlantic in January.  If I don’t microwave a hot pack to put at the base of my bed my feet stay frozen for hours.  At that point, a second reflex is triggered.  Involuntary muscle fibers in my legs begin to push my feet laterally, seeking out the warmest spot (snoozing next to me), and my feet come to press up against the legs of my warm-blooded wife.  My relief is only momentary, however, as my wife’s arm reacts with the “swat-your-husband” reflex and I’m forced to find other ways to thaw my digits.

For my part I’m just offering proof to my wife that I indeed possess a warm heart.  Maybe if I just cut out the unsettling violin music and dog howling in the distance she wouldn’t mind my frozen toes so much.  It’s worth a try.