The phrasing of the question immediately made me wonder if cause and effect are getting mixed up. I also kinda suspect at times that 'sleep disorders' are really just based on work/societal expectations. If one could really sleep at any time and/or at the times they're tired (as opposed to fulfilling others' scheduling expecations...i.e. being to work at 6:00, being to school at 8:00, etc.), then many many more of us would display the sleeping behaviors currently designated as being 'disorders'. We'd take many little naps (like our cats), sleep as late in the mornings as our bodies/minds need - without stigma, and we'd stay up way past our 'bedtimes' without others warning us 'you're goinna be sorry...'. And we'd eventually create a sleeping consistency NATURALLY (a consistency that could be used when making decisions about scheduling other big pieces of life - such as work). The 'trick' is to build a life that better fits one's sleeping needs (among other needs) as opposed to tailoring (at times, read: denying) one's primary needs to others' artificial/unnecessary/power-playing expectations/demands (that they sometimes don't meet themselves!). ...Two of the best books I've ever read included community mentality that those sleeping SHOULDN'T BE WOKEN except in extreme emergency (which, of course, didn't include unrealistic work scheduling or phone calls).
What a fantasy, eh?
But speaking seriously (or WRITING seriously ha!) now... I think a better understanding of one's own bio-rhythms helps. Making the decision to pursue a work position that starts at what is to you an ungodly hour is more along the lines of a punishment as opposed to a sound business decision. Also understanding the forces that could impact or change (whether temporarily or permanently) your bio-rhythms helps in decisions re should work hours be changed, should evening classes replace daytime ones, should a 'tricky' meeting or test be scheduled in the morning or the afternoon, when is the best time for you to sleep, do changing seasons affect all the above answers... lots of questions that somehow get completely overlooked in the name of the 'you-get-to-sleep-only-at-my-convenience' tyranny too many of us experience...
And too many folks using the 'disorder' card to condemn behavior they find disagreeable. Waking up several times during a sleep period (which, really, could be construed as natural occurrences rather than the panic-inducing feeling of being cheated our full time of rest), feeling pressured or anxious about sleep, feeling there are things left undone, ...thinking one doesn't sleep 'right'... some of this really just seems yet another way to 'prove' something's 'wrong' with a particular person - and that it MUST be FIXED if one is going to function in society. Some of the expectations themselves need to be questioned (much like, if one doesn't do well on the how-often-do-you-have-sex poll, some conclusion of unwanted deviance is assumed). The way one sleeps could/should be made to seem more appropriate and acceptable if a more human-oriented (read: HUMANE) standard is applied. I've found that if I not only tried tailoring my life a bit more around my abilities (sleeping and otherwise) but ALSO judging my sleeping 'success' with different parameters, it led directly to a decrease in the pressure (and inevitable insomnia). I didn't try living up to someone else's idea of how I should sleep and, so, ended up sleeping much 'better'. 
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It's your Dae today