In fact, to call Brahma 'creator' is a misnomer. He is not different from the creation. It is not that he has created something like how a sculpture is made out of clay. Brahma has transformed himself into creation.
He transforms himself into the creation,stays that way for sometime and goes back to the state of unmanifest equilibrium. A police officer wears his uniform and transforms himself into the police officer from an ordinary citizen. On completion of duty, he removes the uniform and becomes an ordinary human again. The state of creation and the state of dissolution are just two states of Brahma. The manifest and the unmanifest like being awake and being asleep.
A perfect equilibrium of the three gunas - rajas, satva and tamas is the unmanifest state. The three gunas in a state of imbalance is the state of creation.
The dissolution is the state when all the creation is withdrawn unto Brahma himself. He goes back into the unmanifest state. This is when Brahma sleeps.
Brahma's day consists of 4320000000 solar years. This is when the universe is manifest. At the end of it, he goes to sleep. This is called kalpanta pralaya or naimittika pralaya.Then for the next 4320000000 the universe is unmanifest. On his waking up, the universe is manifest again.
In this manner, Brahma lives for 100 years at the end of which there is a mahapralaya. During kalpanta pralaya,the upper four lokas ie:- Maharaloka, Janaloka, Tapaloka and Satyaloka are not dissolved. However during Mahapralaya which occurs at the end of 311,040,000,000,000 solar years even these four worlds become non existent.
At the end of Brahma's life, a new Brahma is ' born '. We do not know how many Brahmas have lived so far.
It has been ( in 2013 - 14 A.D.) 1972949114 years since the present Brahma woke up for the day.
There are different opinions about the age of the present Brahma. Some say he is past fifty while some say he is eight and a half years old.
It is the agitation of the gunas which results in creation. The gunas are personified as Brahma, Vishnu and Rudra. The gunas are mutually attached, dependent and never separate from each other. Since Brahma himself is the three gunas and he has them under his control and they themselves transform into creation, whatever Brahma desires happens or is created.