I wake up sometimes at night unable to move or to call out. It passes off in a second or two. Does this mean I'm at high risk of having a stroke?

No. You are normal. Lots of people have the same sensation. What is happening is you are waking from a phase of sleep in which your muscles are naturally paralysed. For a short time you remain in this state - until you become fully conscious again. You are no more likely than anyone else to have a stroke.

I read recently that all sorts of conditions, from leukaemia to MS, are being linked to lack of exposure to infection during childhood. My children seem to catch everything - will this low resistance help protect them in later life?

Not exactly. In their pre-school years all children seem constantly to catch colds and other infections. That's because they meet so many other children in playgroups and nurseries, and because there are so many cold viruses to catch - hundreds of different ones. By the time we are adults, we are immune to most of them, which is why our colds are less frequent. As for whether children who are exposed to fewer infections are more susceptible to illness later in life, the jury is still out. Yours almost certainly don't have 'low resistance' - the very fact that they get symptoms when they catch colds shows their resistance is normal. The sneezing, coughing, sore throat, snuffly nose and runny eyes indicate that their antiviral attack systems are working - they are produced by the interaction between germs and immune systems.

· Do you have a question for Dr Smith? Email doctordoctor@theguardian.com