Neurophysiology - Sleep

Question 1

Biological Rhythms - Circadian Rhythm

Answer 1

Sleep-wake cycle, 24h and 11m. Supported by pacemaker cells and clock genes (tells you when to sleep).
External cues can influence the pacemaker, to assist in balancing the rhythm:
- Light conditions
- Entertainment
- Synchronization (accustom to waking up and falling asleep at a certain time)
- Internal mental processes (can’t stop thinking about things)

Question 2

Light Input

Answer 2

Photoreceptors in the retina, sends info through the retinohypothalamic tract. Sensitive to wavelengths 484 to 500nm.

Question 2

Suprachiasmatic Nucleus

Answer 2

The pacemaker, sets the circadian rhythm. Perceives light, sends signals for melatonin when light goes down.

Question 3

What is happening in our brain during sleep?

Answer 3

We burn more energy asleep than awake.
We re-experience everything (thoughts, emotions, expectations…) we did during the day and compare it to all other memories we have.
Brain takes away our consciousness to be able to do this. So that we can create memories.

Question 4

What is the pathway responsible for us re-experiencing everything during sleep and comparing it to all other memories? (REM cycle)

Answer 4

AM → HPC → Striatum → AM
AM → LC (NE)
Striatum → Raphe nuclei (SE)

Question 5

Sleep - Definition

Answer 5

Active, natural periodic state of rest where consciousness is completely or partially lost, so that a decrease in responsiveness can be observed.

Question 6

Sleep cycle

Answer 6

Contains multiple cycles (4-6) lasting 55-85 minutes. Each sub-cycle contains 2 phases, REM (rapid eye movement)(5-15min,25%) and NREM(50-70min,75%).

Question 7

NREM Stages (4)

Answer 7

Stage 1: sleep onset, light sleep. 5%.
Stage 2: deep sleep, 45%.
Stage 3&4: slow wave sleep, deeper state of sleep, more stimulation is needed to recover wakefulness. 25%. Sleep spindles appear, REM in 2-3min.

Question 8

REM Phases (4)

Answer 8

Rapid eye movements
Low PNS activity leading to stimulated paralysis
Highest encephalic activity
Formation of dreams.

Question 9

Sleep Spindles - Definition and Characteristics

Answer 9

Burst of oscillatory short synchronized activity, occurs during N2.
- 12-15 Hz
- 0,5-2 secs
- Origin: thalamic reticular nucleus
- Synchronized by thalamocortical interactions.
Associated with dynamic alterations in synaptic plasticity during sleep.

Question 10

Sleep Function Theories (3)

Answer 10

Circadian theory
Recuperation theory
Memory consolidation/sleep promoting learning theory

Question 11

What are the 5 things that happen during completely or partially interrupted sleep that affects rehabilitation?

Answer 11

↑ cortisol → ↓BDNF,GNF, reduce glucose tolerance, increase sympathetic nervous system activity.
Aggravate pain.
↑ heart rate, blood pressure and sympathetic activity magnifying individual’s response to stress.
Fatigue.
↑ risk of psychological dysfunction and mental illness.