Sleep And Memory Flashcards
What are the different biological rhythms
- ultradian
Rest/activity cycle within 24h - infradian
Lasting longer than 24h, reinitializing itself multiple times over a period of few weeks - circannual
Generated endogenously with a length of about 1 year - circadian
Sleep/wake cycle within 24h
Define the circadian cycle
Sleep/wake cycle within 24h. Repeats itself every 24h and 11mn. It is supported by pacemaker cells and «clock genes» such as cryptochrome and period protein.
What can influence the circadian cycle ?
- light conditions (especially blue light)
- entertainment
- internal mental process
- synchronization
Define pacemaker
The suprachiasmic nucleus setting the circadian cycle
How can the suprachiasmic nucleus influence internal organs ?
(Retina—>) SNC —> Hypothalamus —> hypophysis —> internal organs
Define sleep
An active, natural and periodic state of rest where consciousness is completely or partially lost, so that a decrease in responsiveness is observed.
What is the average duration of a sleep cycle ?
From 55 mn to 85mn
Describe the different NREM phases
NREM stage 1 : light sleep/ sleep onset (5%)
NREM stage 2 : deep sleep (45%)
NREM strange 3+4: slow wave sleep (deeper state of sleep = 25%)
What are the features of REM phase
- rapid eye movement
- low PNS activity (stimulated paralysis)
- highest a cephalic activity
- formation of dreams
What are the sleep spindles ?
Burst of oscillatory, short, synchronized activity visible on EEG during N2 characterized by :
- sigma waves (12-15Hz)
- lasting from 0,5 to 2 seconds
- originating from the thalamic reticular nucleus
- synchronized by thalamocortical interactions
This appearance has been associated with dynamic alteration of synaptic plasticity during sleep.
Spindles are specific to each person like a finger prints and influence by gender, age, genetic aspect.
Explain how sleep patter evolves through lifespan
Sleep pattern evolves over lifetime evolving from multiple cycles in a day in newborn to one longer cycle during the night in elderly. Adults undergo approximately 5 cycles in the night.
In one sleep cycle the NREM phase diminishes over time while the REM phase increase.
Briefly explain the circadian theory
Sleep creates a balance between predators and prays
The period of rest would conserve energy and regulate body temperature
BUT : sleep is not energy saving, other animals not sharing space with predators also sleep
Briefly explain the recuperation theory
Sleep would support the recovery of some energy and therefore assist global metabolism
During sleep the body can activate metabolism related to growth
BUT : growth hormone is not only release during sleep and sleep costs energy
Briefly explain the memory consolidation theory
Sleep support the process of memory consolidation
Sleep promotes the process of learning
NREM is involved in declarative memory consolidation
REM is involved in procedural memory
BUT : no correlation has been made within individuals that sleep lees or more and their learning abilities
What are the risks of sleep deprivation ?
- increase in cortisol
- decrease in glucose tolerance
- increase in sympathetic nervous system activation magnifying the response to stress stimuli
- increase in HR and BP
- increase in fatigue or fatigue perception during the day
- increased risk of psychological disfunction or mental illness
Why is sleep habit important for rehabilitation
Sleep habits must be included in patient clinical history as sleep deprivation can lead to numerous disorder imparting the rehab process.
What are the 3 main types of memory ?
- short term
- long term
- sensory
What are the different types of sensory memory ?
- haptic
- iconic
- echoic
What are the different types of long term memory ?
- implicit : non-declarative
- explicit : declarative
What are the types of explicit long term memory ?
- episodic
- semantic
What are the types of non-declarative long term memory
- procedural
- priming
- associative
- non-associative
What are the types of short term memory ?
Working memory
What are the 3 stage of memory process ?
1) encoding
Creating a context from inputs based on perception, experience and expectations
2) storing
Keep the information to be used in short or long term depending on the usefulness of the information
3) retrieving
Ability to replicate information stored spontaneously or under prompting
What is the memory span ?
Number of items a individual can recall in a working memory test