Is it permissible for a Muslim to sleep four hours, then ask Allah for sufficiency, and strive a little, and ask Allah for understanding and help to succeed?

A Muslim is required to take means (to achieve something) and not to rely on them, for it is one of Allah's sunan (ways) that results are ordered upon causes. Texts have been revealed that indicate this, such as Allah's saying to Maryam: "And shake toward you the trunk of the palm tree; it will drop upon you ripe, fresh dates." And the Prophet's (peace and blessings be upon him) saying to the Bedouin: "Tie it and rely [on Allah]." So, whoever takes means, even if they are few, and relies on Allah, has complied, for taking means is an act of worship, and relying on them is shirk (polytheism).