Extreme genetic outliers still need 5, maybe 4 hours of sleep to function.
Going all the way down to 2 hours of sleep is doable for short bursts, but it will catch up with even the genetic outliers before long.
Many of these people are just exaggerating for effect. If you have poor time management, poor accounting for where you spend your time, and an erratic sleep/wake schedule, it's easy to get confused about actual sleep durations. Some people also use stimulants excessively during the week and then crash on weekends, but they'll only tell you about the nights where they barely slept.
Some people learn to normalize sleep deprivation and coast on a diet of frequent naps. If you take 30-90 minute naps a couple times a day you can coast for a long time on 2-3 hours in bed at night, but you're still sleep deprived. Those weird polyphasic sleep schedules that claim to reduce your need for sleep are simply normalizing sleep deprivation and masking it with naps throughout the day.
Finally, there's a common phenomenon where people misperceive some of their sleep time as being awake: https://en.wikipedia.org/wiki/Sleep_state_misperception This is a common explanation when people claim they didn't sleep at all on a certain night. It's not uncommon for people to claim extreme insomnia, but then sleep 6+ hours as soon as their sleep is objectively monitored.
In short: You can't trust self-reported sleep times. Especially not when someone feels they have something to gain by claiming minimal sleep.
Going all the way down to 2 hours of sleep is doable for short bursts, but it will catch up with even the genetic outliers before long.
Many of these people are just exaggerating for effect. If you have poor time management, poor accounting for where you spend your time, and an erratic sleep/wake schedule, it's easy to get confused about actual sleep durations. Some people also use stimulants excessively during the week and then crash on weekends, but they'll only tell you about the nights where they barely slept.
Some people learn to normalize sleep deprivation and coast on a diet of frequent naps. If you take 30-90 minute naps a couple times a day you can coast for a long time on 2-3 hours in bed at night, but you're still sleep deprived. Those weird polyphasic sleep schedules that claim to reduce your need for sleep are simply normalizing sleep deprivation and masking it with naps throughout the day.
Finally, there's a common phenomenon where people misperceive some of their sleep time as being awake: https://en.wikipedia.org/wiki/Sleep_state_misperception This is a common explanation when people claim they didn't sleep at all on a certain night. It's not uncommon for people to claim extreme insomnia, but then sleep 6+ hours as soon as their sleep is objectively monitored.
In short: You can't trust self-reported sleep times. Especially not when someone feels they have something to gain by claiming minimal sleep.