Circadian Misalignment

Question 1

What is Circadian Misalignment?

Answer 1

Refers to out of sync endogenous rhythm (body clock) and the Sleep wake cycle

Question 2

What are the two types of misalignment? What is the difference?

Answer 2

Phase Advance - Results in the event ocurring earlier
Phase Delay - Moving the event to a later timepoint

Question 3

What is Tau (τ)? How does Chronotype effect Tau?

Answer 3

Tau refers to endogenous rhythm

Early chronotypes have a shorter tau (shorter endogenous rhythm)
Late chronotypes have longer tau (longer endogenous rhythm)

Question 4

Compared to morning type, the evening type demonstrates…?

Answer 4

2.5x more likely to report poor/fair general health (due to decreased SE)
- Increased rate of Type 2 diabetes
- Increased prevalence of Hypertension

Poorer lifestyle choices

Question 5

What are the two Circadian Rhythm Disorders?

Answer 5

1. DSPD - Delayed Sleep Phase Disorder
2. ASPD - Advanced Sleep Phase Disorder

Question 6

What is DPSD? Who is commonly affected? Why does it occur?

Answer 6

Delayed Sleep Phase Disorder
Affects adolescents - Occurs during puberty

Results due to a biological delay in the circadian rhythm
- Also a slow buildup of sleep pressure –> making it harder to fall asleep

Question 7

What is APSD? Who is affected? Why does it occur?

Answer 7

Advances Sleep Phase Disorder
Affects Older adults - due to the body clock ageing

Caused by the circadian timing being relatively earlier compared to he conventional bedtime

Results in a shifting of the bedtime to an earlier time

Question 8

What are treatments for APSD and DPSD respectively?

Answer 8

APSD - evening light exposure delays the circadian rhythm (by supressing melatonin)

DPSD - Morning light exposure - advances the circadian rhythms

Question 9

What is social Jetlag?

Answer 9

The misalignment between the individuals work schedule and their internal schedule (sleep cycle)

Question 10

What is jet lag?

Answer 10

A discrepency between the ‘body clock time’ and the ‘real time’ of the new environment

Question 11

What are effects from jetlag?

Answer 11

• Lack of alertness
• Sleepiness
• Hunger
• Can cause constipation
• Loss of appetite

Question 12

What direction is harder to adjust to? Why?
(Travel Direction)

Answer 12

Flying East

As the day is shorter and its harder to adjust the circadian rhythm

Question 13

Effects of shift work

Answer 13

Obesity
Dyslipidemia (high cholesterol)
Hypertension
CVD diseases
GI disorders
Cancers (particular bowel)

Question 14

What happens to energy expenditure during nightshift work?

Answer 14

After consecutive nightshifts there is a reduction in energy expenditure due to sleeping for most of the day as a result from sleep deprivation

Question 15

What affect does Shiftwork have on glucose? Why?

Answer 15

Causes glucose intolerance

Insulin is released at lower rates during the night
Causing less glucose is released (BLUNTED) to be taken from the blood and into the muscles of tissues

Hence leaving larger amounts of glucose in the blood

Question 16

Affect of shiftwork on Triglycerides and snacking

Answer 16

Taking a night snack leads to a higher TG level in the blood
As a result from blunted insulin release less can be broken down

Causing Dyslipidemia

Question 17

Why is nocturnal feeding incompatible with circadian timing?

Answer 17

• intestinal, gastic emptying rate and kidney and liver activity are all low
• Reduce insulin release –> resulting in less breakdown off glucose and TG