i'm always very skeptical about claims like that, for three reasons:
1. people who claim to work perfectly with less than 7 hours of sleep regularly are often used to it but actually slightly under-perform (in regards to their maximum efficiency) without noticing the difference.
2. there's a bit of societal pressure to sleep less; people sleeping 8-9 hours are sometimes seen as lazy. thus people sometimes falsely claim to sleep less than they actually do (or see pt. 1), which reinforces the original point.
3. a couple of very smart and/or successful people sleep very little at night because they're so productive and successful and sleep would take time away from this - what they forgot to mention are the frequent naps throughout the day.
you are right though that everyone's different. not only genetically - mental, physical and emotional exhaustion differ between jobs and hobbies. though i agree with some others here that sleeping much more than 10 hours regularly may be a sign of health problems or - nowadays more likely due to ubiquitous screens - poor sleep quality.
i'm always very skeptical about claims like that, for three reasons:
1. people who claim to work perfectly with less than 7 hours of sleep regularly are often used to it but actually slightly under-perform (in regards to their maximum efficiency) without noticing the difference.
2. there's a bit of societal pressure to sleep less; people sleeping 8-9 hours are sometimes seen as lazy. thus people sometimes falsely claim to sleep less than they actually do (or see pt. 1), which reinforces the original point.
3. a couple of very smart and/or successful people sleep very little at night because they're so productive and successful and sleep would take time away from this - what they forgot to mention are the frequent naps throughout the day.
you are right though that everyone's different. not only genetically - mental, physical and emotional exhaustion differ between jobs and hobbies. though i agree with some others here that sleeping much more than 10 hours regularly may be a sign of health problems or - nowadays more likely due to ubiquitous screens - poor sleep quality.