i just looked at the info section of Insomnia within Cydia and it only talks about supporting up to iOS 4.x, same applies to Insomnia Pro
i also looked on a couple of compatibility lists and not seeing anything there
if you are ready jailbroken you can go to the app/tweak details and select 'Change Package Settings' > 'Show All Changes' and set to 'ON'. this will show you when it has been updated within Cydia even when you do not have it installed
also, if i were you i would email the Dev to see what his/her plans are on updating, if at all. sometimes they have to be poked & nudged to update their work [
indiekiduk@gmail.com ]