It depends on your biochemistry to a large degree. Some people need hardly any sleep, some do _much_ better work if they sleep a full night's sleep, which can be defined anywhere between 6 and 10 hours. Some people do well on a 24-hour clock, some don't. Minor sleep disorders are common and often not diagnosed.
Don't worry about anyone else (one of the luxuries of a lot of tech jobs), find the schedule that leaves you feeling alert and awake and able to get things done. If you need 8 hours of sleep to be able to code the next day and not walk through the day in a haze - that's you. If you do well keeping a fixed schedule and not deviating, that's great. But if not, don't fight it, listen to your body.
Similarly, some people can code for 10, 12 hour stretches. Some people stop doing useful things after 4 hours without a serious break. Experiment, find what works for you, and _do not_ expect other people to work like you do. Focus on end goals, not processes.
He means that some people do well going to sleep and getting up around the same time every day and some don't. (My hackers go to bed later every day, so their bedtime wraps around the clock often.)
Don't worry about anyone else (one of the luxuries of a lot of tech jobs), find the schedule that leaves you feeling alert and awake and able to get things done. If you need 8 hours of sleep to be able to code the next day and not walk through the day in a haze - that's you. If you do well keeping a fixed schedule and not deviating, that's great. But if not, don't fight it, listen to your body.
Similarly, some people can code for 10, 12 hour stretches. Some people stop doing useful things after 4 hours without a serious break. Experiment, find what works for you, and _do not_ expect other people to work like you do. Focus on end goals, not processes.