... but not in the middle of the night.
As I've got older, I've found that little bouts of nocturnal restlessness in the legs department have become more common. Apparently it's called "restless legs" syndrome (RLS), which for me presesnts as a rather unpleasant, hard-to-resist feeling that you just have to move your legs, sometimes accompanied by having your legs jerking & twitching while you're asleep. (Which then wakes me up, alas!). Trying to relax doesn't seem to have any effect, & the whole thing can make it quite hard to drop off to sleep.
For a while I thought it was 'just me', but apparently up to 10% of the over-65 population (in Western countries, anyway) suffer from this syndrome, with women more susceptible than men. In fact, in a recent paper describing new work on identifying genetic markers for susceptibility to RLS. Winkelmann et al. (2011) identify it as "one of the most common neurological disorders." As you might expect in a syndrome with neurological underpinnings, at least some of the genes implicated in RLS are involved in neuronal transcription pathways. However, it's a complex issue as there may also be links with iron deficiency (there's an interesting question: are people with iron-deficiency anaemia more likely to suffer from RLS than the general population?)
It's even got a name: Willis-Ekbom disease. I really must check with my siblings as researchers estimate that about 60% of cases are familial ie there's a genetic component: so far 6 gene loci are known to be linked to "restless legs", with an autosomal dominant pattern of inheritance & variable 'penetrance' (that is, the trait isn't expressed in everyone carrying the mutation).
And what can one do about it? Well, I guess there's always the pharmacological solution, if sleep disruption becomes a significant problem. But apparently you can also get relief by giving in to the urge to move your legs, so I'll give it a go (trying not to kick the little black dog on the foot of the bed as I do so!).
Winkelmann J., Czamara D., Schormair B., Knauf F., Schulte EC, et al. (2011) Genome-Wide Association Study Identifies Novel Restless Legs Syndrome Susceptibility Loci on 2p14 and 16q12.1. PLoS Genetics 7(7): e1002171. doi: 10.1371/journal.pgen.1002171