Delayed Sleep Phase Disorder — What is it?
He’s a night owl. He’s not a morning person. He doesn’t do mornings. Sure, that fits lots of people. But when it’s really extreme, chances are the person might have DSPS.
The “normal” internal clock makes people fall asleep somewhere around 9 to 11PM and wake up somewhere around 5 to 7. That’s their “sleep phase.”
Someone with a delayed sleep phase might not be able to sleep until 2 or even 4 in the morning. For them to go to bed and fall asleep at 9pm is as realistic as an average person doing so at 5pm.
The thumbnail explanation I’ve found works for most people is this: Delayed Sleep Phase Syndrome is sort of like permanent jet lag. Pretty much everyone knows what jet lag is and can sort of extrapolate what it’d be like if it didn’t go away.
It’s worth noting that there’s also an Advanced Sleep Phase Disorder, where people fall asleep earlier and wake up earlier (say 6 pm til 4 am). From what I’ve seen in admittedly spotty research, it’s less common than the delayed version, and seems to have a less severe impact on the lives of people who have it (people who go in to work early are viewed as productive, after all. 
)
Key characteristics of DSPS
- Sleep-onset and wake times that are intractably later than desired
- Actual sleep-onset times at nearly the same daily clock hour
- Little or no reported difficulty in maintaining sleep once sleep has begun
- Extreme difficulty awakening at the desired time in the morning
- A relatively severe to absolute inability to advance the sleep phase to earlier hours by enforcing conventional sleep and wake times.
–International Classification of Sleep Disorders
You can read more about Delayed Sleep Phase Disorder and other sleep disorders here:
- http://www.sleepdisorderchannel.com/dsps/
- http://en.wikipedia.org/wiki/Delayed_sleep_phase_syndrome
- http://en.wikipedia.org/wiki/Circadian_rhythm_sleep_disorder