Tags: Body clock, Circadian rhythm, Disability, Japanese study, Non-24, Prevalence, Sleep disorder
About 50% of the totally blind have Non-24-hour Sleep-Wake Cycle Disorder while it is very rare among sighted people. People with Non-24 cannot adjust to the environmental 24-hour cycle.
If Hayakawa et al. are to be believed, there have been only 96 cases of N24 in sighted people reported in studies, worldwide, ever. The first 39 were reported in 26 separate studies dated 1970-2003. Hayakawa’s group reported on 57 cases in a report in 2005*. These 57 were diagnosed in Japan in 1991-2001. So what have I learned from that paper?
Are there equally many men and women? No, there are more than two and a half times as many men.
Is Non-24 about as common as the other Circadian Rhythm Disorders (CRDs)? No, the other CRDs together, primarily DSPS, are six times as common.
Do people with Non-24 have anything else in common physically? No. Eye examinations, blood counts, serum biochemistry, electrocardiography, electroencephalography and brain MRIs show nothing special.
Socially? 89% were unmarried and 39% were unemployed.
Had they any health problems in common before the onset of free-running? 28% had psychiatric problems (obsessive-compulsive, adjustment, schizoprenia, anxiety or depression and often associated social withdrawal), not remarkably higher than the general population. But more than a fourth had DSPS before developing Non-24.
How old were they at the onset of Non-24? 86% were ten to twenty-nine years old, none younger than ten. Sex had no effect on the age of onset. (None of the subjects was over 50.)
Do the hours of sleep correlate to the length of the endogenous circadian cycle? Most of the subjects’ cycles were between 24.5 and 25.5 hours, with only one having a cycle longer than 26.5 hours. Subjects slept between less than 7 hours to more than 12, with the majority sleeping 9-11 hours. But there was no correlation between the period of the sleep-wake cycle and sleep length, and neither was affected by sex nor employment status.
How debilitating is the disorder? “98% had a history of disturbed social functioning due to inability to regularly attend school or work.”
Do people with Non-24 often develop psychiatric problems after the onset of the disorder. Yes, but depression only, not the other disorders. “It is possible that these patients had tried to adapt themselves to their social life and failed, leading to psychological stresses that could have precipitated their depression.”
How does Non-24 in sighted people differ from that of people who are blind? The blind generally have a shorter circadian period, and it doesn’t fluctuate over time. In sighted people, the period tends to be longer when sleep onset is in the daytime than when a person falls asleep during nighttime.
*Tatsuro Hayakawa, Makoto Uchiyama, Yuichi Kamei et al. Clinical Analyses of Sighted Patients with Non-24-Hour Sleep-Wake Syndrome: A Study of 57 Consecutively Diagnosed Cases. SLEEP 2005;28(8):945-952
Next post: 62. Psychiatric misdiagnosis of N24
Tags: Disability, DSPS
People do! Some of them are, in fact, quite annoyed at words like sufferer and disability. They’ve found night work or flexible work. They are often geeks, artists, authors etc., who can be their own bosses. Some are happy with their rather ordinary swing shift or graveyard shift jobs and don’t aspire to being the daytime boss.
One I know about starts work at midnight. He does his daytime stuff after getting off work: shopping, health club, dental appointments; all between about nine and noon. He goes to bed at one p.m. without fail, seven days a week. Works out fine, he says.
The choice requires a lot of strength. Explaining it all ad nauseum to everyone doesn’t work, so you have to learn to let all sorts of “helpful” comments just roll by, stick to your guns and insist: ”This is the way I am.”
Any significant other must accept it completely. Any employer must also learn that the occasional morning meeting or training session will not be acceptable.
I know I’m sounding a bit skeptical about this solution, but I’m worn down by decades of not knowing what the problem was. My education prepared me for day jobs only. Society wasn’t 24/7 in my day, and there wasn’t any Internet.
The great advantage, for those who manage this, is that they don’t waste energy and talent fighting against, apologizing for and messing up their innate rhythms. Go for it!
Tags: Diagnosis, Disability, DSPS, Thanks
When you often cannot get up on time, you are seen as unreliable, irresponsible, careless, selfish and worse. As long as neither you nor anyone else knows that there may be a real reason for this behavior, it is all too easy to believe that you are, in fact, all those things. And it doesn’t get better as youthful resilience fades. Been there, done that.
How, then, can some friends offer help and support through it all, year after year? Real help, as in ‘phone calls at 7, daily for months. Organized help, with meetings, even. Are these friends naive, even foolish? Are they just being “nice”? Can you trust their judgement, when they are willing to support a seemingly lost cause?
My friends were delighted, as I was, when a diagnosis was defined. They were justified, could relax and leave the nitty-gritty to the sleep specialist who’d finally popped up.
I haven’t really figured it out yet, after these months of studying DSPS and pondering on how my friends could, somehow, have known. My good news, a recognized disability, was almost overwhelming to me. But they’d “known” all along. I am so grateful.
Tags: ASPS, Body clock, Chronobiology, Chronotype, Disability, DSPS, Eveningness, Genetic mutation, Japanese study, Light therapy, Morningness, Non-24, Prevalence, SAD, Sleep architecture, Sleep disorder
There are a great many sleep disorders. I read recently that an official list of them had been pared down to about 70. Many have to do with not getting enough sleep, or getting sleep of poor quality by several criteria. Some have obvious causes, such as chronic pain, frequent stops in breathing etc.
My interest is in the timing of sleep as my sleep seems otherwise normal. As the experts put it, I have normal “sleep architecture”. (For a good, short explanation of sleep architecture — stages and brain waves — see this page from Feinberg School of Medicine at Northwestern University in the USA.)
Nearly all of us can reset our clocks daily, adjusting the various rhythms to 24 hours. As much as I’ve read about it, I’ve not found a good enough explanation for being able to adjust to 24 hours while not being able to adjust to sleeping midnight to eight or so.
I’m not immune to the light/dark cycle. I need to get up at noon. I fly 8 hours east or west, go through jet lag like anyone else and within days I need to get up at noon in the new location. This is built in. I’m not the only one. I’d just like to understand it better.
A Japanese paper (2004) suggests these possible mechanisms:
- reduced sensitivity of the oscillator to photic entrainment,
- an intrinsic period beyond the range of entrainment to the 24 hour day, and
- abnormal coupling of the sleep/wake cycle to the circadian rhythm.
One of the most rare disorders which occurs naturally is called Non-24. Sufferers simply(?) live on a 23, 25 or 26 hour cycle, getting up one hour later each day for example, thus coming in sync with the earth’s rotation every few weeks. Their rhythms are in sync internally, just not with the light/dark cycle outside. Most, but not all, of these people are blind.
ASPS, Advanced Sleep-Phase Syndrome, is also rare. These people fall asleep and awaken much earlier than normal. The disorder runs in families, and an American family has been studied intensively the last few years. Research on their genetic mutation was published in 2001. “Detailed sequence studies of the candidate human gene, hPer2, in the affected family members, revealed a key change in a single amino acid — from serine to glycine — at position 662 in the hPer2 protein.” The alteration “occurred in the portion of the hPer2 protein that governed binding to an enzyme called casein kinase one-epsilon (CK1e ).” In animal models, this enzyme regulates “proteins involved in controlling the length of circadian rhythms.”
Now this is beyond me, but it would appear that these disorders may be genetically programmed. Though ASPS is rare, it seems reasonable that researchers start there, since one can compare the DNA of people who are related to one other.
Another disorder which may be related to the others is Seasonal Affective Disorder, SAD. Sufferers are normal in summer, have problems of mood, weight gain etc. when days get shorter and can often be treated successfully by bright light therapy. It seems likely that they may have a mild form of ASPS or DSPS which is “treated” by morning/evening daylight when days are long.
Diurnal preference, spoken of as “morningness”, larks, and “eveningness”, owls, is also a subject of study, the field of chronobiology. This is, reasonably enough, connected to one’s circadian rhythms. However, it does not appear that ASPS is an extreme morningness chronotype nor DSPS an extreme eveningness chronotype. The internal relationships among the various rhythms do not place these conditions on a simple continuum.