Be honest at all times.
Lies lead to nothing but trouble. Being known as trustworthy is an excellent trait to maintain and essential to having integrity.
Fully adjusting to a new sleep cycle can take up to 21 days so don’t give up if you feel tired after switching to 5-hour nights. The “required” 8 hour/night is for normal people. So figure out how much sleep you really need and adjust accordingly. As enjoyable as sleep is, waking existence is much more fulfilling and efficient. If this really sparks your interest, check out alternate sleep cycles with which you can be fine off of 2 hours of sleep per day.