UN Blind Mole Rats SCN and Sleep Discussion

I’m working on a psychology question and need the explanation and answer to help me learn.

1. Why has evolution enabled blind mole rats to synchronize their suprachiasmatic nucleus (SCN) activity to light, even if they cannot see well enough to make use of it? 

2. What are the stages of sleep? During which part of a night’s sleep is REM most common? 

3. Infants alternate between short waking periods and short naps. What can we infer about their neurotransmitters?

4. According to the neurocognitive hypothesis, why do we have visual imagery?