From your description (can't see much from the image I am afraid) I would lean towards psocids, aka book lice (Order: Psocoptera),
which look like this:
Note the long antennae - the are also variable in colour depending on species and developmental stage. They prefer it to
be a little damp rather than bone dry and feed on microscopic moulds. They can be a bit of a nuisance, but are harmless.
I agree that is the most likely answer. Indoors you can have several very small species that can go unnoticed for a long time because some of them shun light and others are generally too far away to be noticed (you don't inspect your walls that frequently).
I suspect that they are Tropical Bird Mite, Ornithonyssus bursa. They will almost certainly be associated with a birds nest nearby (loft space, cavity wall) and infest fledgling birds. They are able to bite us too but are unable to feed long term from us. Infestations usual disperse shortly after the birds have fledged.