Health and Well-being: Lecture 3 - Light health and well being (NON imageforming)

Question 1

What are the major pathways for light?

Answer 1

1. Primary optic tract

2. Retinohypothalamic tract

Question 2

What is the retinohypothalamic tract?

Answer 2

The tract by which we perceive the biological effects and behavioral effects of light
Works with ipRGCs

Question 3

What are the non-image forming effects?

Answer 3

• Circadian effects ——> light impinges on cognition and health via consolidation of human sleep wake cycles
• Acute effects ——> light directly impacts on sleep, mood, physiology and cognition

Question 4

What are circadian rhythms?

Answer 4

• Metabolic processes cycle alternately through high and low activity (24 hours)
• Also internal biological clock
• —> suprachiasmatic nucleas in hypothalamus
• —-> 24 hour cycle
• —> clock resets ever day

Question 5

Consequences of shortened sleep are….?

Answer 5

Sleepiness + microsleeps
Weight gain
Social skills and humor
Physical activity
Concentration and memory
Mood swings
Sleep and mental health
Immune functioning

Question 6

Drivers and modulators of sleep and wake cycle

Answer 6

Circadian pacemaker

Hourglass Homeostat

Both: driven by chemical and hormonal processes
Work together to make sure you are awake for hours

Question 7

What is the circadian pacemaker?

Answer 7

Image with blue graph
24 hour cycle
Zeitgeber that is reset on daily basis --> uses light for that
Produces cortisol to keep you aware
Peaks in the early morning

Question 8

What is the Hourglass Oscillator (Homeostat)

Answer 8

Under behavioral control
Sleep pressure that you have been building during the day disappears very fast at around 11
As evening comes closer, melatonin procedure starts and cortisol gets lower
Melatonin helps you sleep

Question 9

What is melatonin?

Answer 9

Helps you sleep at night
Peaks during the night
Only present during sleep
Can be accurately influenced by light
Will stop producing when exposed to bright light at night