Circadian Rhythm & Sleep Disorders

Question 1

Circadian Rhythm Sleep Disorders

Answer 1

Disturbances that lead to sleep disorders may be caused by:
● A naturally occurring change or a malfunction of biological mechanisms or
processes regulating the sleep–wake cycle
● A mismatch between an indi dual’s sleep–wake cycle and the day–night
cycle of their physical en ronment
● A mismatch between an indi dual’s sleep–wake cycle and the sleep–wake
schedule required by their school, work or social schedule.

Question 1

Sleep Disturbances can lead to a Sleep Disorder

Answer 1

Sleep Disorder: an ongoing sleep disturbance causing distress or impairment to everyday life.

The most common type of sleep disorders are:
Circadian Rhythm Sleep Disorders: a sleep disorder invol ng sleep disturbance that is primarily due to a mismatch between an indi dual’s sleep–wake pattern and the pattern that is desired or required

Question 2

Types of Sleep Disorders

Answer 2

• Delayed Sleep Phase Syndrome (DSPS):
• Advanced Sleep Phase Disorder (ASPD)

Question 3

Delayed Sleep Phase Syndrome (DSPS)

Answer 3

A condition in which the major sleep episode is delayed in relation to the desired sleep time or what is considered a conventional time
● Natural tendency to go to sleep later and therefore wake up later than what is normal according to ‘society’s clock’.
● Onset of the entire sleep–wake cycle is significantly delayed, oen by 2 or 3 hours
Main symptoms of DSPS:
● Sleep-onset insomnia
● Difficulty awakening at the desired or necessary time, and excessive
sleepiness.
Sleep Onset Insomnia is characterised by
● Difficulty falling asleep despite hang adequate time and opportunity for sleep.
● Tossing and turning and lying awake when trying to sleep earlier than their desire to fall asleep.
○ This causes anxious thoughts and stress when trying to sleep - resulting in insomnia.
● When required to wake up earlier than desired, by an alarm, they are unable to do so and feel very sleepy for a period of time.

Question 4

Delayed Sleep Phase Syndrome tends to emerge or worsen during adolescence and continue into early adulthood

Answer 4

Why is DSPS more common in adolescence?
During adolescence, the release of melatonin is delayed for up to 2 hours. Melatonin release is controlled by circadian rhythms, which are impacted by both internal and external cues, including light levels.
It is thought that lifestyle factors like homework demands, a er school acti ties, and exposure to blue light can also impact sleep times. A lack of sleep is then exacerbated by early school start times

Question 5

Advanced Sleep Phase Disorder

Answer 5

Circadian rhythm sleep disorder characterised by a shift of the major sleep episode to an earlier time compared to desired or conventional sleep times, resulting in sleep onset and awakening much earlier than desired and excessive sleepiness
Typical sleep onset times are between 6 pm and 8 pm, and wake times are between 1 am and 3 am. These sleep onset and wake times occur despite the person’s best efforts to delay sleep to later hours.
● When sleep occurs on the advanced schedule, it’s essentially normal in quantity and quality for the person’s age.
The overall effect is persistent sleep deprivation and daytime sleepiness. In turn, they experience significant distress and/or impairments in important areas of everyday life. The severity may worsen depending on school, work or social obligations.
● ASPD is a rare disorder but more common among older people (about 1% of males and females in middle age or older).

Question 6

Shift Work Disorder

Answer 6

Circadian rhythm sleep disorder due to work shi fts being regularly scheduled during the usual sleep period; work shi fts overlap with all or part of the sleep period, requiring adjustment of sleep and wake times to the work times
Symptoms of Shi Work Disorder:
● Insomnia when trying to sleep
● Excessive sleepiness when meant to be awake and alert

Question 7

Treatments of Circadian Rhythm Sleep Disorders through Bright Light Therapy

Answer 7

Bright light therapy (aka phototherapy): timed exposure of intense but safe amounts of light (sunlight or artificial) to the eyes
● Helps align a person’s sleep-wake cycle with the schedule they desire/require
● Achieved by discouraging melatonin production How its Done:
● A light box is commonly used, and treatment administered at home
● Light will be transmitted to the SCN to influence melatonin secretion
● Requires a number of sessions over a number of days and exposure may last
from 15 minutes to two hours