Why is it hard to measure sleep straight away?
First night phenomenon - don’t sleep well in a new room at first
Pre sleep alpha waves…
Occur before sleep. They are bursts of 8-12Hz activity in low amplitude/high frequency waves that are normally seen when awake
The four stages of sleep from an EEG are…
Progressive - they increase in amplitude and decrease in frequency
Sleep spindles - 1 or 2 second bursts of 12-14Hz waves
A K complex - a single large up and then down deflection
They form an ongoing cycle throughout the night.
REM sleep is where…
Dreaming occurs. 80% of people report dreaming when they awake from REM sleep.
If someone is awoken 5-15 minutes after entering REM 83% of them are accurate in how long they have been asleep
50-60% of people reported water in their dream if they were awoken with water whilst in REM
Recuperation theory of sleep
Being awake disrupts homeostasis, the optimal biological set point) and sleep restores these energy levels
Evolutionary theory of sleep
Sleep is not a reaction to disrupted homeostasis but evolved to prevent accidents and predation at night. People got what they needed to get done during the day. Sleep is not needed to stay alive.
Sleep in animals…
There are difference between species which are not related to body size or temperature. This is not consistent with recuperation theories.
Youngstedt and Kline (2006) little or no effect of exercise on sleep duration
Evaluation states that sleep in animals is related to…
How vulnerable you are asleep and how much time they spend eating during the day
Sleep deprivation in humans; recuperation theories
Predict that there will be an increase in physiological or behavioural disturbances.
Cirelli (2006) showed that sleep deprivation …
Influenced mood, physiological function and molecular function
Curcio (2006) sleep deprivation had effects on…
Executive functions such as assimilating changing information, updating plans and reference memory.
Recuperation theories say missed sleep must be regained.
People recover well from sleep deprivation. Randy Gardner stayed awake for 260hrs, had 14hrs sleep on his recovery night and then his sleep pattern returned to normal.
REM deprivation occurs when an individual is awoken when they enter REM. studies have shown…
Webb and Agnew (1967) preventing REM made the body want it more
Brunner (1990) causes a transient rebound, individuals spend more time in REM after deprivation.
Sleep deprivation in animals have been tested by putting rats on a turntable above water…
After several days the rat died. A post mortem showed that they had swollen adrenal glands, gastric ulcers and internal bleeding.
Areas of the brain involved in sleep; hypothalamus
Constantin von Economo looked at patients that had died from virus encephalitis lethargica.
He found that difficulty sleeping was associated with damage to the anterior region
Difficulty staying awake was associated with damage to the posterior region