Circadian Rhythm Sleep Disorders VCE PSYCHOLOGY 3/4 (Chapter 7A)

- Chapter 7A Edrolo Textbook VCE PSYCHOLOGY

Sleep disorders

Disturbances to typical sleeping and waking patterns.

Circadian rhythm sleep disorders

Sleep disorders that interfere with the typical regulation of the circadian rhythm of sleep, leading to a change in the sleep-wake cycle. 

Causes of circadian rhythm sleep disorders

• Can be due to a biological issue, (such as the sleep-wake shift that occurs in adolescents)

• Lifestyle changes (such as shift-work)

Effects of Circadian Rhythm Sleep Disorders

• Amplified emotional responses

• Fatigue

• Irritability

• Reduced ability to concentrate

• Disruptive to an individual’s lifestyle (e.g being late to places, feeling sleepy at abnormal times, making it difficult to complete tasks)

Delayed Sleep Phase Disorder (DSPS)

A type of circadian rhythm sleep disorder in which sleeping and waking occur later than usual

What is Delayed Sleep Phase Disorder (DSPS) caused by?

• Misalignment between external and internal cues.

• External cues are received at an appropriate time, but internal cues are not.

• This causes melatonin secretion to occur later.

• Therefore sleep and wake times occur later than appropriate.

Delayed Sleep Phase Disorder (DSPS) example

An individual receives the external cues of light in the morning and dark in the night, but they do not receive internal cues properly in the morning and at night.

Advanced sleep phase disorder (ASPD)

A type of circadian rhythm sleep disorder where sleeping and waking occur earlier than usual.

What is Advanced sleep phase disorder (ASPD) caused by?

• Misalignment between external and internal cues.

• External cues are received at an appropriate time, but internal cues are not.

• This causes sleep and waking to be earlier than appropriate, due to melatonin secretion occurring earlier.

Advanced sleep phase disorder (ASPD) example

An individual still receives the external cues of light in the morning and dark in the night, but their internal cues are not being received properly in the morning and night.

Shift work

An occupation that involves working unusual hours, such as working overnight

How does shift work impact sleep?

• Circadian rhythm is constantly changing and adapting to their environment. 

• This often leads to individuals having difficulty initiating sleep and waking while adjusting from one shift to another.

Effects of shift work

• Insomnia

• Fragmented sleep

• Circadian rhythm sleep disorders

• Poorer quality and quantity of sleep

What are shift work disorders caused by:

Problems with external cues as an individual is required to be awake when it’s dark and sleep when it’s light.

Bright light therapy (BLT)

A method used to adjust a person’s circadian rhythm through exposure to a high-intensity light source.

How does BLT work?

• BLT readjusts the circadian rhythm, so that an individual’s sleep and wake times are more appropriate. 

• When an individual is exposed to the light source in the morning, the suprachiasmatic nucleus (SCN) will be signalled, promoting wakefulness through the release of cortisol.

• This will in turn trigger an earlier release of melatonin at night-time by the pineal gland.

• Consequently, the individual will fall asleep earlier at night-time and thus experience a longer and more restful sleep which will benefit the individual the following day.
  

What are 3 factors for successful BLT?

• Timing

• Amount of light

• Safe exposure

Factors for successful BLT: Timing

Light therapy must be done at the right time of day to shift the body clock (e.g. late afternoon for those who feel sleepy too early).

Factors for successful BLT: Amount of light

The light’s intensity and duration must match the person's needs and should increase gradually to avoid side effects.

Factors for successful BLT: Safe exposure

Avoid looking directly at the light and keep a safe distance to protect the eyes and skin.

How can BLT be used for Delayed Sleep Phase Syndrome?

Morning light exposure resets the body clock earlier, promoting wakefulness and helping the person fall asleep earlier at night.

How can BLT be used for Advanced Sleep Phase Syndrome?

Evening light exposure delays the body clock, helping the person stay awake later and sleep in longer.

How can BLT be used for Shift Work Sleep Disorder?

Light exposure before or after work helps shift workers stay awake during work and sleep at appropriate non-working times.