1. EFFECTS OF STRESS ON BEHAVIOUR AND SLEEP
Cortisol: a stress hormone and a wake hormone
Anton Coenen
Radboud University Nijmegen
The Netherlands
Lviv Ukraine
October 5, 2017

2. Effects of stress on sleep

3. Effects of stress on sleep (see bottom trace)

4. The balance between sympathetic and parasympathetic activity
pupil
miosis
The balance between sympathetic and parasympathetic activity

5. Relation between the degree of ‘efficient’ behaviour and the level of arousal (curve of Yerkes and Dodson, 1908) (inverted U-shaped relationship).

6. Stress ↓
HPA axis activation
CRF
Releasing Factor
ACTH
Cortisol
CORTISOL AS A
STRESS HORMONE

7. CORTISOL
AS A WAKE HORMONE

8. The circadian rhythm of cortisol under basal conditions
meal
meal
The circadian rhythm of cortisol under basal conditions

9. A breakthrough: cortisol binds to two receptor subtypes
(Reul and de Kloet, 1985)
Mineralocorticoid receptor Type I
Glucocorticoid receptor Type II
Type I high affinity in limbic structures and hippocampus
Type II low affinity in the same structures and in frontal cortical areas

10. At the peak in the cortisol rhythm, both type I and type II receptors
are activated, while at the cortisol trough there is only activation of the
high affinity type I receptors (after: Lupien et al. 2007).

11. The Type I/Type II ratio hypothesis of cortisol and memory performance
(de Kloet, Oitzl and Joels, 1999)
memory
performance
level of cortisol
When type I receptors are saturated with partial occupancy of type II, there is
maximal memory performance. But when both type I and II are not occupied
(left), or when both are saturated (right), there are memory impairments.

12. 100%Type I 50%Type II
100%Type I 100%type II
0%Type I and II
Proposed analog explanation of the inverted U-shaped relationship) between performance and level of arousal.

13. Cortisol is a adrenal gland hormone that supplies the body for its
activities. It does this also under stress conditions. But high stressful
conditions, associated with high cortisol levels, are adverse.
Cortisol binds to two receptor subtypes: high affinity type I and low
affinity type II, also with differences in location.
It appears that under high cortisol levels when high affinity type 1
receptors are saturated, also type II receptors become saturated.
Saturation of low affinity type II receptors is associated with negative
effects on memory, on performance and on behaviour.