OSA or Official Secrets Act (Chap 213) prevents
unauthorised release of info. However, nothing in the OSA or SAF
act prevents SAF from authorising release of medical records.
Singapore got no privacy law.
I have no experience of anyone actually requesting for such
data though so no idea whether in practice it really happen.
Somnambulism or sleepwalking shouldn't affect day jobs
unless you day sleep but if you try for night watchman or night
security guard, that may be a plus!. Seriously, when applying
for jobs, normally need to go for check up. Most will require
declaration. It is better to check with doctor whether this will
affect the job.
I have relatives who failed medical exam but still got job. Just
have to declare and get exemption. Except for serious cases eg
cancer, HIV, etc, most cases should be no problem but if dun want
to hire, its normally for your and your colleague's safety
reason.