1. The Nature of Sleep This topic includes Sleep stages Lifespan changes
“Outline the nature of sleep” ( 4 marks or 8 marks)
“Outline and evaluate the nature of sleep including lifespan changes” (8 + 16)
“Outline lifespan changes in sleep” ( 4 marks or 8 marks)

2. Quiz on the sleep stages
Two minutes to look over your work

3. The Nature of Sleep
When we are awake our brain waves are of ____ __________
What type of waves are characterised by the EEG in stage one?
What two changes begin to happen physically to the body in stage one?
The Hypnogogic state in stage one may involve what?
What waves occur in Stage 2?
What is a sleep spindle?
At what stage is if difficult to wake someone and sleep walking is most likely to occur?
What is released in stage 4?
REM or stage 5 features what type of waves?
Dreaming is most likely to occur at which stage?
Why is REM sleep known as paradoxical sleep?

4. Answers High Frequency Alpha
Lowering of body temperature and heartrate/Blood pressure
Hallucinations
Beta waves
Peak or cluster of high frequency brain waves
Stage 4
Growth hormones
High Frequency waves
REM sleep or stage 5
Eyes and brain are active but body in a state of paralyses

5. Why do we sleep? Why is sleep important?
What might the approaches suggest about why we sleep?

6. The nature of sleep allows for particular benefits, such as body repair and brain recovery
For instance, the growth hormone released during the 4th stage of sleep enables protein synthesis and cell growth to take place. This is important in the restoration of body tissue because proteins are fragile and must be constantly replaced. (Sassin et al)
Similarly, REM sleep in the 5th stage of the Basic Rest-Activity cycle enables brain recovery. Babies have approximately 50% REM sleep, whereas adult have nearer to 25% which is linked to babies’ rapid brain growth. (Siegal)
This suggests that there are functions of neural development behind the nature of sleep and its stages.

7. Outline the nature of sleep. (8 marks)
Key detail from the markscheme
The nature of sleep conventionally refers to the basic characteristics of sleep. These include its circadian periodicity, the different phases and stages of sleep (REM and NREM, or REM and SWS), the association between REM sleep and dreaming etc.
Different sleep patterns across the lifespan or across the animal kingdom would also be relevant.
Given the problem of defining the ‘nature’ of sleep, a wide range of material could be relevant. These include the functions of sleep, sleep disorders, brain mechanisms of sleep and sleep as a biological rhythm.