Feel like your inner timing is out? You may have a circadian rhythm disorder.

There are a number of disorders of the circadian rhythm that can cause problems with feeling more sleepy that you would expect or having trouble sleeping. They include delayed and advanced sleep-wake phase disorders, irregular and non-24 sleep-wake rhythm disorders and shift work disorder. In this video I discuss each of these disorders to help you better understand how to recognise them and understand general principles of used in treatment.

Video Timeline:

  • 00:00 – 01:25 When the circadian rhythm isn’t working well
  • 01:25 – 04:00 Properties of the circadian rhythm
  • 04:00 – 05:25 Delayed sleep-wake phase disorder
  • 05:25 – 06:41 Advanced sleep-wake phase disorder
  • 06:41 – 08:14 Irregular sleep-wake rhythm disorder
  • 08:14 – 10:05 Non 24 sleep-wake rhythm disorder
  • 10:05 – 11:12 Shift work disorder
  • 11:12 – 11:43 Summary

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I’ve talked in another video about how the circadian system works when it’s working well and some of the key inputs into the circadian system. In this video, I hope to explain to you what some of the common circadian rhythm disorders are, so you get a feel for what happens when the circadian system isn’t working right.

In essence, when the circadian system is working well, we feel well. Health is good. The body seems to be working well and both central and peripheral clocks are well-synchronised.

If the circadian system isn’t working well, then things just don’t seem to go right. Either we can’t get to sleep at the time we want to get to sleep. We can’t wake up at the time we want to wake up or we get bits of sleep and wake all over the place and other body systems aren’t right either. Temperature doesn’t seem right, how we eat, how the body processes food and appetite and how we open the bowels for example just also doesn’t seem right.

Now the main sleep disorders or circadian rhythm sleep disorders are delayed sleep phase syndrome, advanced sleep phase syndrome, irregular sleep-wake rhythm disorder, non-24 sleep-wake rhythm disorder and shift work disorder and I will talk through each of these briefly to give you an idea of what each of them are.

As I talked about in a previous video, the circadian system has a number of properties. One of the key properties of the circadian system is the length of the circadian system. So per 24 hours, what someone’s intrinsic body clock – so some people have an intrinsic body clock of exactly 24 hours and that person will find they’re waking pretty much the same time every day, just feeling sleepy about the same time every day, not drifting a bit later on weekends or on holidays, not finding they’re waking earlier and not really feeling that they’re having trouble maintaining being awake across the day and being asleep across the night.

However, that’s not the average for people. The average for people is actually to have a slightly longer body clock than 24 hours. It’s around 24 hours and 15 minutes, maybe a touch longer. So we live on a planet that has got a 24-hour cycle. So if intrinsically we’ve got a clock that’s about 24 hours, 15 minutes, every day it’s going to feel like the alarm is just going off about 15 minutes too early.

Now that’s not a circadian rhythm disorder. That’s just being human. So that trouble of when the alarm goes and not feeling like you want to leap out of bed and attack the day the first time the alarm goes, that’s just being human. It’s not that you’re vitamin-deficient or you’re abnormal. But if it’s taking more than 20 minutes, half an hour and you’re really sluggish and still can’t get going, that’s when we start to think about a circadian rhythm problem.

Another important property of the circadian rhythm is what we call the amplitude or think of it as how strong a rhythm that is. If someone has got a really robust circadian rhythm, they will generally at a certain time at night feel like, “Geez, I really need to go to sleep,” and a certain time in the morning start to feel like, “Yeah, I’m waking up and there’s no way I could go back to sleep once I’m up and going and into the day.”

So that’s an example of a robust rhythm. A rhythm that I often see in chronic illness, be it physical illness or mental illness is where that doesn’t have that same robust up and down or amplitude to the rhythm. So people feel like at night time, “Yeah, I’m not particularly sleepy,” and during the day time, “I’m not particularly alert either.” It can feel pretty much the same actually across that 24-hour period. So that’s another example of a property of the circadian rhythm, the amplitude, and then the other property is the period.

Now the third property is the phase and that’s how your circadian rhythm fits to the outside world. This is where the two first circadian rhythm sleep disorders come in. So they’re phase disorders where someone’s intrinsic rhythm is out of sync with the outside world.

Now the most common of these is delayed sleep phase syndrome. So that’s where someone’s intrinsic body clock is running at a later time than the place where they’re living.

An example is – most commonly seen in adolescents where for school reasons, parents may want them to be going to bed at 10:00 and waking up at 7:00 but really they’re not going to sleep until 1:00 and waking up at 10:00.

Now if they’re left to their own devices, say on holidays and follow that pattern, they feel fine. They function well once they’re up at 10:00. They feel pretty normal throughout the day. It’s just that there’s that three-hour offset where they’re getting to sleep three hours later and waking up three hours later than the desired time of waking up.

Now that in itself doesn’t cause a problem if people can live on their own schedules. Not many of us can. So it does cause problems particularly in school where it can manifest as trouble getting to sleep. So a teenager gets put to bed at 10:00 but isn’t going to go to sleep until 1:00 anyway and they’re dragged out of bed at 7:00 which is three hours before their body is really ready to wake up and it’s a bit like trying to wake me up at 3:00 in the morning. You would be heavy-headed and grumpy and take ages to get going.

If you’re parents of a teenager, you will have recognised that. So that’s called delayed sleep-wake phase disorder where the body clock is offset by some hours compared to the desired sleeping time.

The other phase disorder is advanced sleep-wake phase disorder and that’s the opposite where the body clock is a bit earlier than what’s the desired time and that’s actually much less common in sort of younger adults. A little more common as people get older particularly beyond retirement age where people find they might be falling asleep 8:30 PM, 9:00 PM. They’re only going to get around six hours of sleep, so then waking around 3:00 AM and getting distressed about being awake from 3:00 AM when it’s dark. What am I going to do for the rest of the night?

You will know people in the office who have got that, a mild version of that advanced sleep-wake phase disorder because they’re the ones that are always in the office early first thing in the morning, ready to go, ready for action.

If you’re trying to compete against them, schedule the meetings in the afternoon because that’s not a good time for them. They’ve run out of steam by the afternoon and if you’re more a delayed sleep phase or a later night type, you will be really hitting your straps in the afternoon. It doesn’t mean that society is not structured towards those with a bit of a phase advance, that saying, “The early bird gets the worm.” It’s about a 600-year-old saying but still holds true in society today, which is actually structured a lot towards people with this earlier body clock.

The next sleep-wake disorder we will talk about is irregular sleep-wake rhythm disorder. So that’s where there’s more of a – as the name suggests, irregular sleep patterns, so bits of sleep, bits of wake, all over the place. Now the most common times I see that again is in the advanced elderly, particularly people who are getting problems, neurological problems like forms of dementia, like they’ve had a stroke for example, where the regulation of sleep is not as good as where it could be.

The example I’ve got on the screen here is of a diary, again an actigraphy type of diary of someone with irregular sleep-wake rhythm disorder where instead of night time they’re very still and no wakefulness. The night time period is characterised by lots of those bits of black or lots of movements as measured by actigraphy and likewise the daytime rather than being all just being awake, there are bits of white which is bits of sleep.

So it’s bits of wake and bits of sleep just interspersed across the 24-hour period. So people get unpredictable periods of sleep and wake with little short periods of sleep and short periods of wake and it all just mixes in together.

So I generally think of that in older adults but I do see it though in people with physical illness or mental illness and the other group I see it is in illicit drug use, so people either taking amphetamines or people who are self-administering lots of stimulants like drinking lots of caffeine, energy drinks, Red Bull. So if I see that very regular pattern in a young person, it does make me think about being over-stimulated.

The next sleep-wake disorder is called non-24 hour sleep-wake disorder. This is much less common, apart from people that are totally blind because if you don’t have any light input to cue in the circadian rhythm, and light is the strongest input to synchronise the circadian rhythm, your body clock will default to its own intrinsic period length, that 24-hour, 15-minute type of length.

So people find they just gradually sleep later and later and later and later around the clock, day after day, and that was what was found in those experiments in the late 1930s, 1940s when people put themselves in a cave away from all other cues because they slept that 15 to 20 minutes later every single day.

Now the other time people get a non-24 hour sleep-wake rhythm disorder is if they’ve got a very long rhythm like a 25-hour rhythm for example. Some teenagers get that. I see it in some people with depression and I also see it just rarely in people who don’t seem to have any other illnesses at all but have this body clock that just makes them sleep later and later and later each day and they tend to cycle around the clock and it might take them three, four weeks to cycle around the clock.

How that manifests or the symptoms are often – they have one or two weeks where, yeah, my rhythm is about right and I feel not too bad. But then I have two or three weeks where I’m sleeping during the day or awake all night, constantly tired and just can’t seem to work out what’s going on.

Once we plot out the rhythm, using a sleep diary like the example on the screen, you can clearly see the periods of sleep here marked in black gradually drifting later and later each day. So over a two-week period, they’re drifting by around 12 hours which means their body clock is around a 25-hour body clock and then the last circadian rhythm disorder we will talk about is shift work disorder.

A large proportion of the population work shifts around 20 percent of the working population and then around 10 percent of those – so about two in a hundred people in the general population – get what’s called shift work disorder and that’s where people have trouble getting to sleep or feeling that they’re more tired than they would expect as a consequence of working shifts.

Now shift work can mean that you miss out on sleep, that you’re not getting as much sleep and it can also mean that you’re trying to sleep at a time when your body clock is actually trying to keep you awake.

So you can feel like everything is out of sync, not unlike jetlag as well as you’re just not – a bit underdone in terms of not had enough sleep.

On the screen is an example of shift rotations where somebody is doing night shifts and day shifts and it really shows that there’s little blocks of sleep that are hard to come by in unpredictable times and people often find then they can only sleep for three or four hours when they get an opportunity for sleep and sleep then is not of great quality. So they end up being both sleep-deprived and their body clock being thrown out as if they jetlagged.

So I hope that has given you an idea about the different circadian rhythm sleep-wake disorders. You may recognise some of those disorders in terms of your own symptoms, and you can discuss that with your health professional. Have a look at the other videos that talk about then how to manipulate your circadian rhythm and manage your circadian rhythm if you think that circadian rhythm disorders may be part of what’s happening in your case.

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