Chapter 7B

Question 1

sleep disorder

Answer 1

Sleep disorder: a disturbance to typical sleeping and waking
patterns. We will focus on one category of sleep disorders:

Question 2

circadian rhythm sleep disorders

Answer 2

Circadian rhythm sleep disorders are sleep disorders which
interfere with an individual’s typical circadian rhythm, leading
to changes in the sleep wake cycle.

Question 3

circadian rhythm sleep disorders can result in

Answer 3

• excessive sleepiness during the day
• an inability to initiate sleep at night
• effects of partial/total sleep deprivation (the ABCs)
• Lifestyle disruptions e.g., being late, unable to complete
  tasks etc

Question 4

types of circadian rhythm sleep disorders

Answer 4

• delayed sleep phase syndrome
• advanced sleep phase disorder
• shift work

Question 5

delayed sleep phase syndrome

Answer 5

A type of circadian rhythm sleep disorder in which sleep and waking occur
later than usual, ie: the sleep-wake cycle is DELAYED

Question 6

what causes DSPS

Answer 6

+ Specific causes are not fully understood, however is occurs when
there is a misalignment between external and internal cues that
regulate the circadian rhythm.
+ This means that the external cues occur at an appropriate time, but
the internal cues do not.

• Melatonin is released later, so an individual will feel tired later, go to bed
  later, and therefore wake later → a DELAY
  in their sleep-wake cycle, which is out of
  sync with the typical day-night cycle

Question 7

DSPS is common in adolescents and young adults, why?

Answer 7

Biological
* Changes in hormone secretions:
* 1-2 hour delayed release of melatonin
Psychological and social behaviours
* Lifestyle changes/independence
* Social and academic demands change → part time job, homework,
parties, mobile phone etc

Question 8

advanced sleep phase disorder

Answer 8

A type of circadian rhythm sleep disorder in which sleep and waking occur
earlier than usual, ie: the sleep-wake cycle is ADVANCED

Question 9

What causes ASPD

Answer 9

Specific causes also not clearly understood, however like DSPS, it is a
misalignment between external and internal cues that regulate the
circadian rhythm.
+ Individuals will sleep earlier than appropriate, due to melatonin
being secreted earlier
+ They will also wake earlier than appropriate

+ Sleep quality and quantity are generally unaffected (as with DSPS),
however, even if sleep is delayed to a more appropriate later time,
they will still wake up early resulting in sleep deprivation

Question 10

who experiences ASPD

Answer 10

+ It is a rare disorder, but more common amongst older
people
+ Circadian rhythms and sleep-wake times tend to naturally
advance (start earlier) in older people which may explain
the increased prevalence.

Question 11

shift work

Answer 11

Shift work: any occupation that requires individuals to
work during hours which are inconsistent with the rest
of society, for example:
* Working overnight (fixed schedule)
* Rotating shifts (eg: one week of mornings, one week of nights)

Question 12

how does shift work impact a indiviudlas sleep wake cycle

Answer 12

Shift work impacts an individual’s sleep-wake cycle as
their 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.

Question 13

sleep problems due to shift work

Answer 13

+ Shift work is considered to be a cause of sleep problems, rather than being a sleep
disorder itself. It results in a range of sleep-related issues, such as:
▪ Insomnia – difficulty falling and staying asleep
▪ Fragmented sleep – sleep occurs in naps rather than a single sleep episode
▪ Circadian rhythm sleep disorders – external cues are out of
sync/misaligned, eg: working in highly lit environments at night
▪ Quality and quantity of sleep affected
While ASPD and DSPS are caused by problems with internal cues, shift work
disorders are caused by problems with external cues as an individual is required to
be awake when it’s dark and sleep when it’s light.

Question 14

treatment of circadian rhythm sleep disorders with: Bright light therapy

Answer 14

+ Circadian rhythm sleep disorders, and the effects of shift work, are
characterised by difficulties and misalignments of circadian rhythms
+ Bright light therapy, or phototherapy, is a treatment for these disorders.
+ Bright light therapy is a method used to adjust a person’s circadian
rhythm through timed exposures to a high-intensity light source

Question 15

bright light therapy for circadian rhythm sleep disorders

Answer 15

+ A high intensity, artificial light is used (a light box)
+ The light box must produce light intensity of 2500
to 10,000 lux (5-20x brighter than room light) to
be considered BLT (normal room light is 100-500
lux, sunlight around 4000 to 100,000 lux!)
+ This will advance or delay sleep, depending on
time of use

Question 16

how does bright light therapy work?

Answer 16

+ Light will act as a zeitgeber to readjust the circadian
rhythm so that sleep and wake times are more appropriate

Question 17

bright light therapy - the process

Answer 17

+ Bright light therapy requires a number of
exposure sessions (15mins to 2 hours) over a
number of days until the sleep-wake adjusts
Factors essential for successful Bright Light Therapy:
* to use the light at the right time of day
* for the right amount of time
* at the right intensity
* safely – don’t look directly at it!

Question 18

factors essential to successful bright light therapy

Answer 18

• appropriate timing of exposure sessions
• the right amount of light
• safe exposure

Question 19

appropriate timing of exposure sessions

Answer 19

Bright light therapy must occur at the right time in order to make a person
feel awake at the right time. For example, people who feel sleepy earlier
than appropriate, such as by 5pm, can conduct an exposure session in the
late afternoon or early evening in order to help them stay awake and fall
asleep later at a more appropriate time.

Question 20

the right amount of light

Answer 20

The intensitv of the light and the length of exposure sessions must be
appropriate to the person’s disorder and desired changes to their circadian
rhythm. The intensity and length should also be built up gradually in order
to avoid negative side effects like headaches.

Question 21

self exposure

Answer 21

A person should not look directlv at the light, and their face should be an
adequate distance away from the light source.

Question 22

bright light therapy for DSPS

Answer 22

An individual is exposed to the bright light source in the morning at
an appropriate waking time. This will act as an external cue to the
suprachiasmatic nucleus and promote wakefulness, by sending signals to
release cortisol. This will help the suprachiasmatic nucleus send signals
for melatonin release at an earlier, more appropriate sleeping time, thus
promoting sleep.

Question 23

bright light therapy for ASPD

Answer 23

An individual is exposed to the bright light source in the evening when feeling
sleepy, to act as an external cue to the suprachiasmatic nucleus and promote
wakefulness. This will then help the suprachiasmatic nucleus send signals for
melatonin release at a later, more appropriate sleeping time, thus promoting
sleep. Additionally, this will encourage the suprachiasmatic nucleus to signal
cortisol release later in the morning at a more appropriate time.

Question 24

bright light therapy for shift-work related sleep disorder

Answer 24

The use of bright light therapy for shift work depends on the details and
timing of an individual’s work. An individual is best to be exposed to the
bright light source before beginning their shift work, in order to promote
wakefulness when they need to be awake and alert. This will help promote
sleepiness at a later, more suitable time (when they are not required to
work), whether that be during the morning or afternoon.
+ BLT should be used a couple of hours prior to the shift work to attempt to
slow/suppress the release of melatonin.
+ Avoid daylight between end of shift and sleep time. Dark glasses could be used.
+ The workplace could assist employees by maintaining high levels of bright light in
the work environment during night shifts.
+ Similarly, light should be kept to a minimum when returning home from the night
shift, with the bedroom kept as dark as possible to assist with the release of
melatonin to encourage the onset of sleep

Question 25

side effects of bright light therapy

Answer 25

+ Bright light therapy does not seem to produce any major side
effects when used within the proper limits for intensity and time.
+ Minor side effects may include eye irritation, headache, nausea
and dryness of skin