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Sleep-Wake Phase Disorders are medical conditions wherein the human body’s natural sleep-wake cycle or Circadian Rhythm gets affected.

A normal Circadian Rhythm is one where a person sleeps or wakes at roughly the same each day. This cycle depends on a lot of factors like hormone levels and light exposure. The lifestyle of a person also affects his sleep-wake cycle.

When a person has a sleep-wake phase disorder, he or she experiences a recurrent pattern of sleep disturbance. The sleep disturbances that they experience are largely due to either an alteration in their internal circadian timing system. It can also be due to a misalignment between the person’s internal circadian rhythm and the 24-hour social and physical environments.

What are the symptoms of sleep-wake phase disorders?

A person with a sleep-wake phase disorder can experience one or more of the following symptoms:

  • Difficulty falling asleep at night
  • Difficulty waking up in the morning
  • Excessive daytime sleepiness
  • A sleep period that is ahead or behind everybody else’s


It is important to seek the help of a sleep specialist to ensure that a proper diagnosis. It is not uncommon for a sleep-wake phase disorder to be mistaken for another sleep disorder. This is because of symptoms that are similar to those of other sleep disorders. There are several clinical tools used to diagnose such sleep disorders. For example, a person may think that his inability to sleep at his desired sleeping time is due to insomnia when the truth is he has Delayed Sleep-Wake Phase Disorder.

Sleep Diary

The most practical tool is a sleep diary or a sleep log. A sleep diary is a record of someone’s sleep patterns and habits. The information noted in the said diary can be extremely useful for a doctor to make an accurate diagnosis of a sleep disorder. A sleep log can also help a doctor determine if a more thorough sleep study is needed.

A patient maintains a sleep diary for at least two weeks. A patient will record in the sleep diary information such as:

  • The time that the patient went to bed
  • The amount of time it took for the patient to fall asleep
  • The time the patient woke up the following morning
  • The number of times that the patient woke up during the night
  • How refreshing the previous night’s sleep was
  • The amount of caffeinated drink the patient consumed all day
  • The number of alcoholic beverages the patient consumed all day
  • What medications the patient took
  • The activities a patient performed within an hour of getting to bed and rising
  • The amount of time spent exercising and the type of exercises performed

Sleep Actigraphy

Sleep actigraphy is a non-invasive device that can monitor a person’s sleep patterns. It is a cost-effective tool that a person can use to determine a person’s sleep quantity and quality. A sleep actigraphy usually comes in the form of a wristwatch that contains a small accelerometer. It can sense movement while a person sleeps. Since an actigraph is a non-intrusive device, a person can wear it for weeks or even months. They can be integrated on a smartwatch or a separate device. Although they are not accurate enough to detect specific sleep stages, they can still help a sleep specialist determine a sleep disorder.

What are the types of sleep-wake disorders?

Advanced Sleep-Wake Phase Disorder

This is a condition also called Advanced Sleep-phase Syndrome. Just as its name suggests, this is a condition where a person’s sleeping and waking time is earlier than what is normal. Those with this disorder often sleep and wake at least a couple of hours ahead of the normal sleep and wake time.

Delayed Sleep-Wake Phase Disorder

This is the exact opposite of what Advanced Sleep-Wake Phase Disorder does. When a person has this disorder, their sleep and wake times occur on a later time compared to others. Even if the patient went to bed at an earlier time, they won’t feel tired or sleepy and they are likely to stay awake past their usual bedtime.

Sleep-Wake Phase Disorders force a person to sleep and wake during times that are not considered “normal”. As a result, they are often sleepy during wakeful hours. When left untreated, these disorders can have a huge impact on a person’s productivity whether at school or the workplace. Thankfully there are ways to effectively deal with these disorders and minimize their impact on a person’s life.

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