circadian disorders

Question 1

phase delay

Answer 1

difficulty falling asleep and waking up - big chance of leading to insomnia

Question 2

phase advance

Answer 2

early sleepiness, early awakening - social isolation

Question 3

free running

Answer 3

▪ Talked about this in blind people
Shifted sleep schedule every night

Question 4

❄️❄️❄️SEASONAL AFFECTIVE DISORDER

Answer 4

….is a recurrent depressive disorder that occurs in the winter and goes into remission during the summer
○ 6% of adults in USA
10-20% in world..?

Question 5

consequences of sleep disorders

Answer 5

· Can lead to insomnia (especially phase delay) - get anxious because we can’t fall asleep
· Attention, mood difficulties, difficulties in everyday functioning
· Social isolation (especially phase advance and non 24 hour rhythms)
· Long term effects (non specific - follow from sleep deprivation): gastro intestinal, cardiovascular disorders, mood disorders (depression, anxiety), cancer risk

Question 6

why do we say that in and of themselves some circadian disorders might not be a disorder

Answer 6

if you are able to make your own schedule and you get enough sleep you will probably be fine. They become a problem when they misalign with life demands (ie. Not being able to go to bed till 3 am but having to wake up at 7 for work)
…………..

Question 7

endogenous factors

Answer 7

variation in circadian physiology - affecgs instrisnc period and phase of entrainment
- differential sensitivity to morning and evening light or blue light
- neurodegeneration
- blindness

Question 8

environmental and behavioural factors

Answer 8

• school, work, or social schedules
  -caffeine or nicotine use
  -psychiatric disorders
• self selected exposure to evening or mroning light
• feeding times

Question 9

treatment

Answer 9

○ Circadian entrainment - ex. make yourself wake up early all the time so you’re more tired in the evening and its easier to fall asleep
○ Phototherapy (light therapy)
Melatonin

Question 10

phototherapy

Answer 10

Super effective!!! For circadian disorders and for sad
10 000 lux is optimal (mimics outside daylight spectrum)

Question 11

jetlag

Answer 11

Temporary circadian misalignment
- Sleep difficulty
- Digestive difficulties
- Cognitive difficulties

· Requires entrainment to host environment
· To counteract: sleep schedule, meal schedule, light exposure schedule, melatonin

Question 12

social jetlag

Answer 12

Adolescents = the biggest sufferers of social jetlag
- Remember: age different in chronotype
- Natural sleep patterns conflict with school start times
- Study: delaying start of school time makes a big difference in school performance, impulse control, etc

Oversleeping on weekends and under sleeping on weekdays creates bad push/pull routine
· Staying up late on weekends makes it hard to go to bed early for school

Question 13

shift work and social jetlag

Answer 13

○ By definition produces circadian misalignment
○ Is often associated with insufficient sleep
○ Shift workers often “compensate” on days off
○ Opposite problem: bright light at wrong moments suppresses melatonin
Solution: avoiding blue light exposure

Question 14

consequences of social jetlag

Answer 14

Shift work/social jetlag exacerbates any sleep problems you might be predisposed to
· Metabolic effects
· Cravings
· Sleep disorders
· Impaired cognition
· Risk of obesity
Risk of diabetes

Question 15

tolerable social jetlag

Answer 15

+/- 25 minutes

Question 16

solutions to social jetlag

Answer 16

○ Flexible work schedule
○ Later school start
No more daylight savings time

Question 17

fluorescent street lights

Answer 17

• Light pollution
  
  • Don’t use fluorescent street lights!!

Massive inequities:
- Much more light pollution in poorer neighbourhoods in the US
Circadian inequities

Question 18

bright light in icu

Answer 18

..a tough balance
· Too much bright light - lots of ICUs have constant bright light
· Not enough daylight - icu delirium - transient delusional disorder
· Neonate: entraining circadian rhythmicity in preterm infants
○ Improved weight gain
○ Shorter hospital stay

Question 19

circadian disorders and neurodegeneration

Answer 19

• Circadian dysfunction = sleep dysfunction
  
  • Circle of = fragmented sleep -> metabolic changes - neuropathological changes
  • Leads to oxidative stress and increase inflammation
    Neurodegeneration

Question 20

summary

Answer 20

· Circadian rhythms = balance between internal/endogenous rhythms and external/exogenous conditions
· Can be entrained through exposure to zeitgeibers (light, food, physical activity, social cues)
· Involve phase shifts
Involves - scn, iprgc, hypothalamic tract, melanopsin, melatonin, phase shifts, sleep peaks, etc