Image by Gemma Correll
By the end of this module, you should be able to:
- describe how different neurotransmitters influence the
- outline the role of the locus coeruleus and reticular
activating system play in sleep
- explain the stages of the sleep cycle and describe key
waveforms at each stage
- list the key physiological components that differentiate
non-rapid eye movement (NREM) sleep from rapid eye movement (REM)
- explain the relationship between the circadian clock and the
- describe how sleep changes across the lifespan
- list the effects of hypnotic drugs on sleep.
'We spend a third of our lives doing it, Napoleon,
Florence Nightingale and Margaret Thatcher got by on four hours a
night, Thomas Edison claimed it was a waste of
time.' (BBC Science & Nature,
What is sleep?
Sleep is a natural, cyclical alteration of
consciousness that is essential to our normal functioning and
health. During this biorhythmic state of unconsciousness, the brain
becomes less sensitive to external stimuli.
Why do we sleep?
Does it conserve energy or let
the brain 'recharge'?
This is something of a misconception.
Literature suggests that 'sleeping only reduces metabolism and
energy use in humans by at most 5–10% overall'
(Mastin, 2013a). Over an 8-hour period
of sleep, this would equate to approximately 50 kCal (BBC Science & Nature, 2014).
Sleep is necessary for normal functioning and
health. It plays a significant role in brain development and
deficiency of sleep, especially long-term, can lead to serious
health problems. Sleep deprivation hinders brain function,
especially the regions controlling memory, planning, language and
sense of time.
Judgement can also be affected. Research
suggests that remaining awake for over 17 hours reduces cognitive
psychomotor performance to the same extent as that caused by a
blood alcohol concentration of 0.05%, the legal drink driving limit
in the UK (Dawson & Reid,
Sleep deprivation impacts normal physiology,
with consequences on emotional and physical health. Lack of sleep
has many causes and is associated with several conditions,
including: depression, anxiety, obesity, heart disease and type 2
How is sleep different to other states of
Sleep occurs in a predictable pattern. During the shift from
wakefulness to sleep, there is a progressive decrease in
neurological response to environmental, auditory and visual stimuli
from the brain (Moroz et al, 2011
We recommend that you make some notes as you work through
The 'TrOn Notebook' facility can be accessed
throughout the module (allowing you to make notes on each page),
and these notes will be saved in your personal area 'My TrOn', for
future reference. However, you will not be able to print these
notes as one single document.
If you would prefer to make your notes in a
separate document you may wish to download the 'learning notes'
below. This downloadable Word document will allow you to keep a
personalised record of your learning, which you can then save
and/or print for future reference.
the learning notes document for this module