phi

Taking a moment to appreciate one of my several superpowers: sleep. I can go to sleep:

• in a wide range of temperature, light, and noise conditions
  
• at a wide range of times (sustainably, 14 to 19 hours since I last slept, but I can and do stay up for 30 hours and then sleep for 12 to manage jet lag when taking a redeye)
  
• quickly
  
• soundly
  
• for a set amount of time. That is: If I go to sleep intending to sleep for a certain number of hours, that is how long I sleep, without an alarm.
  
• or, until a subtle alarm goes off, if the amount of time I need to sleep is unknown in advance. The alarm can be well below the ambient noise level.
  

I also don't need as much sleep as some people: 7.5 hours a night is generally plenty. I can function on 5 hours for weeks or months at a time and 2 hours for about four cycles. That last one only works if the "up" phase of my sleep cycle doesn't exceed about 17 hours, which means it precesses like mad.

What I can't do is go to sleep within 45 minutes of either sunrise or sunset. Something about that light level kicks off my seratonin. It's my sleep kryptonite.

I've had most of these superpowers since birth, but some of them didn't develop until I started a meditation practice back in 2001 or so.