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Circadian Rhythm Disorders - How a small group of sleep conditions can impact on your life: Part 1

Circadian Rhythm Disorders - How a small group of sleep conditions can impact on your life: Part 1

The circadian rhythm is roughly a 24 hour cycle part of the internal body clock found in humans, animals and plants. The cycle controls when we eat, sleep and other factors which are involved in our day to day lives; our rhythms are mainly affected by external factors with the most prominent factor being light. A prime example of light being a key factor is when we travel into different time zones; after a couple of days our body clock adapts to the time change and we find it easier to fall asleep. A healthy circadian rhythm allows you to do the following:

  • Wake up and fall asleep around the same time every day.

  • Go to sleep and wake up within a certain time frame while still getting the sufficient hours of sleep before the new day begins; this is important for people who work or have something important to attend.

  • Adjust to a new circadian rhythm after a few days, for example starting a full-time job after university generally requires a 9am start; going to bed earlier than usual to adjust to your new rhythm is known as ‘advancing the sleep phase’. The sleep phase in healthy people can be advanced as much as an hour each day.

However, for some the circadian rhythm does not always run smoothly and a small group of sleep disorders known as circadian rhythm sleep disorders are usually to blame; they mainly affect the timing of sleep which can interfere greatly with work, social and school times. For the sufferer, the amount of hours sleep is normal if they are allowed to sleep without any disturbances and wake up with their body clock. Usually the quality of sleep is the same as a person with a healthy circadian rhythm. There are two types of circadian rhythm sleep disorders, these are:

  • Extrinsic – where the rhythm is disturbed by external factors; common disorders are temporary jet lag (also known as rapid time zone change syndrome) and shift-work sleep disorder.

  • Intrinsic – this means the circadian rhythm sleep disorder is built-in in the body clock; the common disorders under this category which we are going to discuss in part one and part two are:

  1. Delayed sleep phase disorder (DSPD)

  2. Advanced sleep phase disorder (ASPD)

  3. Free running disorder (FRD)

  4. Irregular sleep-wake rhythm disorder

Delayed sleep phase disorder (DSPD)

People who suffer from this disorder generally don’t get to sleep till at least two hours after people with healthy circadian rhythms do; for some their normal bedtime is as late as 4am. The sufferers are usually referred to as ‘night owls’ although this is only true to an extent as ‘night owls’ can still wake up early in the morning if they have to. Although this disorder can affect anyone it mainly affects teenagers (Sleep Health Foundation). People who suffer from DSPD find it difficult to wake for the usual working and social hours and can sleep until the early afternoon. Their sleep quality doesn’t suffer as they usually get the recommended 7-9 hours sleep if left alone however, for those that do have a nine til five job their health can be jeopardized.

What are the symptoms of DSPD?

There are various symptoms of DSPD, some of these are:

  • Feeling sleepy and groggy throughout the day – if a sufferer needs to wake up for the usual working hours of a day it can leave them feeling tired and moody throughout the day as they haven’t had the sufficient hours of sleep.

  • Difficulty falling asleep at a desired time – although a sufferer may want to fall asleep around 11pm they can’t; it’s not because they have worry or stress on their mind (signs of insomnia), it’s because their body clock is unsynchronised with the external environment so it still thinks it’s daytime and keeps the person wide awake.

  • Depression and low mood – signs of depression can be apparent if the sufferer doesn’t know how to manage DSPD. If they keep being late or missing work/school it can dampen their mood along with a decrease in their productivity. Some sufferers depend heavily on caffeine and certain medications to help them get through the normal working hours.

  • No signs of other sleep problems – if there are no other sleep problems present, DSPD sufferers should fall asleep at a later time with ease and have little or no awakenings throughout the night. Furthermore if they are given the chance to sleep through the full sleep cycle they will wake up feeling refreshed and alert. Remember DSPD is only a move in the body clock where the sufferer becomes sleepy two or more hours after the usual bedtimes of adults/children.

Treatment of DSPD

You should always visit your local doctor if feel like you are suffering from DSPD as they can guide you in the right direction of treatment, if any is needed. Usually if your doctor can see signs of a sleep disorder they will refer you to see a sleep specialist; some of the treatments may include:

  • Chronotherapy – this form of treatment is usually effective but only when recommended by a sleep specialist. It involves lengthening your sleep cycle for around 3 hours every night and the course should last for seven days. For example if a sufferer ideally wanted to be in bed by 10pm and up at 6am they would go to bed at 4am on the first night then 7am the second, adding 3 hours each day; by the time the seventh day comes it will be 10pm. This form of treatment is very unsociable but highly successful for most so take a week’s holiday or do it during the holidays. However this form of treatment is not for everyone as some find it more troublesome to their sleep cycle and can show signs of insomnia.

  • Bright light therapy – this can be from natural sunlight or a light box. On a morning you will be exposed to the bright light for around 30 minutes to an hour as this helps to reset the body clock and hopefully increase awareness and alertness; on an evening dim lights are recommended. Each person will react differently to this form of treatment so it’s all about trial and error until the desired light exposure is reached.

  • Melatonin – this type of treatment is usually last resort after the other methods have been tested as it’s not fully proven to help with DSPD (UK Health Centre). Read about how to increase your melatonin levels naturally here.

Advanced sleep phase disorder (ASPD)

This disorder runs like DSPD but in the opposite direction meaning sufferers go to bed early and wake up very early in the morning; once they are awake they find it difficult to return back to sleep. The circadian rhythm is programmed earlier to a normal cycle therefore a sufferer can feel very tired early evening (between 6pm-8pm) yet feel very alert and refreshed between 3am-4am. In comparison to DSPD this disorder mainly affects older adults. It doesn’t affect the sufferer’s work life although it can affect evening social activities. The symptoms are very similar to DSPD:

  • Daytime fatigue – the sufferer is waking up very early in the morning so by the time the afternoon comes they feel very tired and run-down.

  • Insufficient sleep – sometimes when the sufferer is waking up in the early hours of the morning they find it difficult to fall back to sleep sometimes resulting in less hours sleep than usual. For example one night they may go to bed at 8pm and wake up at 1am resulting in a total of five hours sleep. These nights could be a sign of early morning insomnia; read more about insomnia here.

  • Increase the risk of depression – the sufferer is missing out on evening social events which can cause depression as they may feel alone.

Again, treatment is very similar to DSPD by first contacting your doctor if you notice any unusual patterns in your sleeping habits. They may refer you to see a sleep specialist who may then try and reset the body clock to a normal time by going to bed a little later each night (around 30 minutes per night). This method is helped using bright light therapy but instead of using bright light in the morning the therapy is used on an evening for around an hour or so and usually stopped about 30 minutes before bedtime.


As with all sleep problems you should keep a sleep diary for a couple of weeks before visiting your doctor so they can look through the diary and see if they notice any patterns; it will also help give them a better understanding of the disorder you may have. A sleep diary should include what time you went to sleep and woke up, any disturbances, how you felt etc…

Keep checking back on our blog for part two of the circadian rhythm disorders

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