i canty sleep more than 6 hours?

Sleep depends on age,,young folks sleep a long time at night,it lessens as with age. Do you go to bed fairly early as that makes a difference.Do you exercise so your body is tired and ready for rest ?

all i can say is best way to get rid of sleeping disorders is excercise...alot of it...
both mental and physical
this type of workout leads to hard core sleeping
even if the results arent seen immediately the body clock soon kicks in and wala your sleeping properly agian
personally i went through this phase where i would be tiered but unable to fall asleep
that is because the body just isnt exauhsted enough to drop
try it for a week see if it works

Sleep timings vary from age to age and it also depends on your day to day activity.Rest if you are feeling anxiety then you must concern with some doctor.

Just dont think about it too much! Dont focus on it cuz it makes it harder. Try to start watching a movie at 10 pm and juz give your mind to it
For me I cant sleep more than 9 hours, if I do that I get headaches that they dont go away and I feel tired all day.
For me when I think about something constantly it keeps happening to me so I stop thinking about it and it usually goes away.

May be the problem you are facing due to the depression. If there is something like this then meet your doctor. If not then exercise daily will give you a good and sound sleep. After getting tired body and mind need sleep.