You should only wear them for a couple of hours a day for a week or so at first.
Also carry eye drops with you, they will help immensely.
I'd suggest using the hydrogen peroxide (Clear Care) cleaning solutions too, rather than the saline based ones. Some people can develop allergic reactions to the preservatives used in the saline based solutions over time. No reason to expose yourself to that. Plus the hydrogen peroxide based ones are the only real true rub-free solutions.
What contacts are you using? I used Acuvue and the hurt like HELL!!! Switched to O2 Optics and WOW...extended wear contacts and they are COMFORTABLE! Never notice Im wearing them...been wearing the same pair for 6 months, never have taken them out! And yes its safe...Ive had more than one doctor tell me so...as long as they arent irritating you you can keep them in as long as youd like, even when sleeping and what not.
HIGHLY RECOMMEND O2 OPTICS! I was not paid to endorse them, they are just that damn good!
I wouldn't endorse one brand like that. Everyone's eyes are different and everyone responds differently to different brands. The best advice is to try as many different brands as you can until you find one that is the most comfortable for you.
Acuvue is the most comfortable for me...
Eye doctors are usually sent free samples by the manufacturers, so you should be able to try them all out.
I'd also suggest changing doctors if one said it was ok to sleep in your contacts. That's just opening yourself up to infections.