You will freeze! I sometimes leave my a/c on all night at 25C/low fan but I live in Cyprus.
As others have said...Having the air con on 16c is burning money and will keep the pump running all night. Set it to around 22-24 for sleep because you naturally get colder as you sleep and 16c you will be freezing.
My aircon uses about 1kw and cools down to 18c and costs about 10p per hour to run. It sounds cheap to run but if you run it for 10 hours a day over a month it soon adds up.