1. n. The phase of one's waking-sleeping schedule with respect to the standard 24-hour cycle. This is a useful concept among people who often work at night and/or according to no fixed schedule. It is not uncommon to change one's phase by as much as 6 hours per day on a regular basis.
"What's your phase?"
"I've been getting in about 8 P.M. lately, but I'm going to wrap around to the day schedule by Friday."
A person who is roughly 12 hours out of phase is sometimes said to be in 'night mode'. (The term 'day mode' is also (but less frequently) used, meaning you're working 9 to 5 (or, more likely, 10 to 6).) The act of altering one's cycle is called 'changing phase'; 'phase shifting' has also been recently reported from Caltech.
2. 'change phase the hard way': To stay awake for a very long time in order to get into a different phase.
3. 'change phase the easy way': To stay asleep, etc. However, some claim that either staying awake longer or sleeping longer is easy, and that it is *shortening* your day or night that's hard (see wrap around). The 'jet lag' that afflicts travelers who cross many time-zone boundaries may be attributed to two distinct causes: the strain of travel per se, and the strain of changing phase. Hackers who suddenly find that they must change phase drastically in a short period of time, particularly the hard way, experience something very like jet lag without traveling.