This is a very good answer on the effects and theories on the purpose of sleep.
Some interesting tidbits:
Evidence is accumulating that complex nervous systems, and especially
the brain, perform and benefit from internal maintenance activities.
Some of these maintenance activities, such as "synaptic network
stabilization" occur at the cellular level. Others, such as memory
consolidation or the proposed memory transfer between brain areas,
occur at the whole brain level.
Theorized uses of sleep
- Restoring neurons biochemically
- Rescaling the connection strengths of
synapses in the brain's neural networks to facilitate easier learning
the next day. This might include rewiring activity (growing synapses).
- Consolidating (reorganizing and restructuring) memories.
- Transferring memories from the memory-specialized fast-learning brain
area (the hippocampus) to the higher-capacity more cognitively
powerful area (the cerebral cortex)
"At the whole animal behavioural level, the functions of sleep seem
clear: energy is saved, performance is restored and (in humans) affect
becomes more positive. Such findings have led to the universal
acknowledgement that sleep restores brain function."
From my personal experience sleep is essential for focus, productivity, muscular and skeletal system recovery, memory, energy levels, mood and a lot others.
There are a lot of different sleep methods from just reducing sleep time to doing sleep intervals (Taking 30 minute naps every 2-3 hours I think). I haven't seen any supporting claims that these methods do work for a significant part of the population.
My recommendation is to start with the accepted approach: Sleeping ~8 hours at night time. I personally recommend not sleeping later than 11pm. Evaluate how you respond to that schedule and then start making modifications and see how you react to it. That way you can objectively determine what sleep pattern works the best for you.
Make sure to make small adjustments, giving your body enough time to adjust to the new sleep schedule, and record as objective data as possible such as mood/energy levels/focus etc.