SHED SOME LIGHT || Ask the Expert: Misconceptions about Circadian Rhythm Disorders

Today SHC hosts a great summary of misconceptions about circadian rhythm sleep disorders from Peter Mansbach, PhD and president, founder and webmaster of the Circadian Sleep Disorders Network. 

Peter Mansbach PhD, President
of the Circadian Sleep Disorders
Network

_______________________________


I would like to clarify some things about Circadian Rhythm Sleep Disorders that are often glossed over or not widely recognized.

First and most importantly, there are TWO problems contributing to these disorders. One is that the timing of the body's clock is off. The other is that the sufferer is UNABLE to shift that timing.

Many people are "night owls": their body clocks run late, they want to go to sleep later than is customary in our society, and they get up later in the morning. But many night owls can, with a little attention to proper sleep hygiene, adjust their schedule to be able to work normal daytime hours.

This preference rises to a disorder only when the night owl is UNABLE to adjust their hours without more rigorous treatment. It is called Delayed Sleep Phase Disorder, or DSPD [1].

What do I mean when I say a person is unable to adjust their sleep hours? I mean that they can set their alarm and force themselves to get up at the desired time, day after day, but when it comes time to sleep, they cannot fall asleep. Their mind becomes active, they toss and turn for hours until their body clock finally decides it's sleep time. By sticking with this schedule they are not getting enough sleep, night after night. They are increasingly tired during the day, find it difficult to function, and this causes long term damage to their bodies. Yet they still do not fall asleep at the desired bedtime.

I've been asked many times to get up early for a doctor's appointment, repairman visit, relative's kid's baseball game, whatever. "Can't you just set an alarm and get up, just this once?" ("Just this once" ... right.) Well, yes I could--but don't try to hold an intelligent conversation with me that early, because I can't even process what you say, let alone formulate an answer, and that's if I don't crash the car on the way there. Once, when I did try to get up really early for an urgent business meeting, I drove onto the highway and found myself facing two lanes of cars coming at me at 60 mph: I had accidentally driven onto an off ramp. Not recommended.

What causes Delayed Sleep Phase Disorder? DSPD refers to a set of symptoms, and there may be different underlying physical abnormalities in different patients. These may include long intrinsic circadian period, lack of sensitivity to light, over-sensitivity to light, deficiencies in the ipRGC cells [2] of the retina, lack of melatonin production, long elimination time of melatonin, differences in timing of sleep relative to internal circadian rhythms, differences in tolerance to phase mismatch, and possibly others. So it's not necessarily a single disorder with the same cause in all patients.

DSPD is treated using bright light in the morning, avoiding light in the evening, and/or taking melatonin. Timing is critical. Yet not everyone responds well to treatment. Some researchers mentioned a 40 percent success rate, though treatments have improved since then. Why so low? I suspect because different people have different underlying causes, and the researchers tried a one-size-fits-all treatment.

How many people are we talking about? The studies that I'm familiar with estimate the prevalence of DSPD at about 0.15 percent, or 3 in 2000. That's half a million adult Americans! It's also a lot more prevalent in teens, perhaps 7 to 10 percent of them, most of whom will grow out of it.

Regarding Non-24-Hour Sleep-Wake Disorder (Non-24), I want to distinguish between Non-24 in blind people versus in sighted people. The Non-24 diagnosis refers to a set of symptoms in which the patient cannot entrain their schedule to a 24-hour day. Instead, their sleep time progresses later and later each day, going all the way around the clock. It is also called Free Running Disorder.

We know what causes Non-24 in blind people: lack of response to light. People's body clocks do not run at exactly 24 hours. On average, they run about 10 minutes longer than that [3], but exact timing varies among individuals. The body syncs its clock to the 24-hour day-night cycle through light entering the eyes [4]. In blind subjects, this synchronizing often does not occur [5].

In sighted people, the causes of Non-24 are believed to be similar to the causes of DSPD. I think we need to view these as two different disorders--Sighted Non-24 and Blind Non-24--since they have such different causes.

I'll close by touching on what I call "the myth of the good night's sleep" in relation to circadian rhythm sleep disorders. 

The literature describes DSPD and Non-24 by saying that, if allowed to sleep on their bodies' natural schedules, patients would sleep well and arise fully rested. 

For many people this has not been the case. Although they function far better on their own schedule than if they force themselves into a normal sleep schedule, they may still sleep fitfully, or be tired during their wake time.

Thanks to Tamara Sellman at SleepyHeadCENTRAL for this opportunity to post.



[1] Earlier medical classifications referred to Delayed Sleep Phase Syndrome, DSPS, and this is still a popular term. The current classifications use the term Delayed Sleep Phase Disorder, DSPD.
 [2] ipRGCs: Intrinsically photosensitive retinal ganglion cells. These cells in the eyes are receptive to light even in the absence of the rods and cones in the eye used to "see" light.
 [3] Early studies suggested 25 hours, but that has been discredited. It resulted because the study subjects used light in the evening.
 [4] There was an experiment which claimed light at the back of the knees could entrain the body clock, but that data could not be replicated, so the theory has been abandoned.
 [5] It can still occur, even without visual perception, if the ipRGCs in the retina are unaffected.

SHED SOME LIGHT on CIRCADIAN DISORDERS

In order to understand what a circadian rhythm disorder is, you need to know what circadian rhythms are.

Circadian rhythms are also referred to collectively as "the body clock," as they mark the way in which the human body processes time cues from the environment. These time cues include sunlight and seasons and temperature changes.

Our bodies are influenced strongly by these exterior cues, as they help to inform many internal processes in the human body as well, including sleep drive and digestion, among other things.

Hence, our bodies cycle in tandem with these rhythms, which occur following the same 24-hour pattern that represents one Earth day.

Think about it: The typical human being rises with the sun and goes to bed after the sun has set. When this very basic programming of the human body is diverted, many basic biological functions can be changed, thwarted or otherwise negatively impacted.

Research into sleep health and circadian rhythm dysfunction continues to show consistently how these kinds of disruptions to our rhythms can lead to cardiovascular problems, slower metabolism (leading to obesity), higher risk for cancer, and connections with mental health problems.

Some common circadian rhythm disorders can come as the result of lifestyle choices: jet lag occurs because of air travel across time zones, and those who work the graveyard shift can have a hard time achieving "recovery" sleep after working long overnight hours.

But some circadian rhythm problems are the result of internal disruptions.

Teenagers often has delayed sleep phase disorder, in which their drive to sleep launches later in the evening than their younger or older peers; these changes in "sleep phase" are brought about by chemical responses inside the bodies of teens that relate to their rapidly changing brain and body biology.

Keep in mind, delayed sleep phase problems are not just reserved for teenagers, but for anyone who can't fall asleep at a "typical" hour. Extreme night owls of all ages can find this problematic for keeping morning appointments or getting to work on time if it means they must cut short their nightly sleep due to delayed sleep phasing.

Elderly people often have advanced sleep phases, the opposite of what adolescents experience, which can explain why they are in bed by 6pm at night.

But again, people of any age can also suffer advanced sleep phasing, which can get in the way of work and family life as it often means these people cannot stay awake to participate in social time or work shifts that are scheduled in the early evening.

In addition, there are people whose rhythms do not match the 24-hour cycle... their days are typically longer than 24 hours, and this makes it difficult for them to live normal lives. They suffer because their sleep-wake cycles can become extremely desynchronized with the rest of the world.

Finally, the person who suffers from irregular sleep-wake phase suffers from the interruption of at least 3 sleeping periods during their waking day.

You can see how having intrusive periods of sleep or wakefulness at the wrong times of the day can make life hard for some. Employers and educators function on fairly regular working periods, so jobs can be hard to keep. Falling asleep at inappropriate times can be embarrassing, can lead to relationship stress, and can keep circadian rhythm disorder sufferers from leading full lives; they might even be dangerous.

Employers are starting to honor flex hours to respond to the needs of those who have dysfunctional circadian rhythms. Scheduling in hospitals and other workplaces where 24-hour shift work is the norm can help to give these employees a fair chance to recover from their overnight schedules so they can be better, safer workers. It's not unheard of for corporations to now have a nap room available to those who may need to catch a few midday winks.

Later school start times are one attempt to help teenagers to endure their naturally later sleep phases so they can be more productive and alert in class and so that they can avoid the sleep deprivation that delayed sleep phase can cause, which can lead to automobile accidents from drowsy driving and poor decision making in social situations.

Still, families can struggle when one or more members has a circadian rhythm disorder. Circadian dysfunction can lead to misunderstandings, unfounded assumptions about laziness, concerns that the sufferer has mental health problems, and mistakes that can make a home unsafe (kitchen fires, bad falls, and harm to unsupervised children are all potential risks).

To learn more about circadian rhythms, please visit the Circadian Sleep Disorders Network for in-depth information on each of these conditions and for resources for treating these conditions and raising awareness.

Sleep Disorders 101 || Is Your Body Clock Broken? There's Help For You

• Do you have problems sleeping on a "normal" schedule? 
• Do you sleep a few hours on, rise for a few hours, then repeat this cycle over and over again? 
• Are you an extreme night owl or morning lark? Does this have a negative impact on your life?
• Do you constantly experience jet lag? 
• Do you find your work on the night shift is messing with your sleep rhythms?

If you answered yes to any of these question, you might have a circadian rhythm disorder (CRSD or CSD). A circadian rhythm disorder is described as a neurological condition in which you have trouble synchronizing the sleep-wake cycle with the day-night cycle. CRSDs can wreak havoc on work and family life, but fortunately, they are treatable.

How do you find out if this is what's plaguing you? First, see your doctor and get tested and diagnosed. You can't do much until you know exactly why your sleeping habits are the way they are, and it will be important for you to rule out other hidden health conditions or even personal sleep habits which might be leading to these kinds of symptoms.

Treatments for CRSDs vary widely and depend upon your specific condition. For more information about CRSDs in general, and their treatments, you are encouraged to visit the Circadian Sleep Disorders Network.