BSc Zoology / Course details

Year of entry: 2024

Course unit details:
Clocks, Sleep & the Rhythms of Life (E)

Course unit fact file
Unit code BIOL31681
Credit rating 10
Unit level Level 3
Teaching period(s) Semester 1
Available as a free choice unit? No


This unit will introduce you to the study of biological timekeeping by examining how neural mechanisms of circadian rhythms, arousal, metabolism and sleep interact to dictate daily and seasonal variations in behaviour and physiology. You will cover a range of topics with a particular focus on the neuronal basis for circadian timing and sleep in mammals, how these are regulated by environmental light and how the internal clockwork influences the rest of the brain and body in health and disease.


Unit title Unit code Requirement type Description
Sensory Systems BIOL21341 Pre-Requisite Recommended
Motor Systems BIOL21332 Pre-Requisite Recommended


Principally, to (a) introduce students to the study of biological timekeeping, (b) examine how neural mechanisms of circadian rhythms, arousal, metabolism, and sleep interact to coordinate behaviour and physiology.

Learning outcomes

Students should be able to:• Understand the neural and molecular bases for circadian rhythmicity in both simple and complex neural systems• Explain how physiology and behaviour changes from day to night• Describe how brain state changes across the sleep-wake cycle and the importance of these different states in cognitive performance and brain health.• Describe the neural and genetic bases for sleep and arousal disorders.• Describe how metabolic states and circadian clocks interact.• Describe how environmental light information is captured by the eye and relayed to circadian centres in the brain and the influence of this light information on sleep and physiology.• Describe how circadian clocks develop in the brain and how they decline with age.• Develop an understanding of how biological timekeeping mechanisms evolved and how they influence many facets of physiology and behaviour.


In this unit, students are introduced to biological rhythms (ultradian, circadian, and infradian) and the basic principles of biological timekeeping. The molecular basis for the circadian clock in animals and its major ‘clock’ genes/proteins and their roles are defined. Particular focus is placed on the neuronal basis for the circadian timing system in the mammalian brain and how specific photoreceptors capture environmental light information to regulate these brain clocks. The neurochemicals used to communicate timing information to the brain and body are identified as are the effects of transgenic knockdown/out of these signalling systems on physiological and behavioural rhythms. The impact of the circadian timing system on cognition and sleep is evaluated with emphasis on how rhythmic electrical activity varies with brain states such as waking and dreaming. The interaction between metabolism and circadian clocks is explored, particularly from the viewpoint of body weight regulation. Further, to provide understanding of the real-world impact of biological clocks, circadian controls of immune function and interactions with the ageing process and disease states are explored, as are the effects of light and daylength on seasonal physiology.

Employability skills

Analytical skills
Students are encouraged to analyse the validity of conclusions of experiments presented during the lectures.
Oral communication
Students are encouraged to answer questions during lectures.
Students are directed to read primary literature in topics raised during the lectures and to independently search for new findings in those topics.
Written communication
Essay questions in examination.

Assessment methods

Method Weight
Other 5%
Written exam 95%
2 hour written examination (95%) - choose 2 from 6 essay titles. Other - eLearning core multiple choice mid-semester test (5%).

Feedback methods

References to specific studies relevant to each lecture, announcements via Blackboard 9, post-exam guidance. A compulsory eLearning core multiple choice mid-semester test worth 5% will provide students with insight into how well they have understood course content. Students will also be offered the opportunity to receive feedback on an optional pre-exam essay question. Further feedback will be provided at an end of course question and answer review session.

Recommended reading

Dunlap, Loros, DeCoursey (eds) (2003) Chronobiology: Biological Timekeeping. Sinauer PressRefinetti, R (2006) Circadian physiology (2nd Edition). Taylor & Francis Group

Study hours

Scheduled activity hours
Assessment written exam 2
Lectures 18
Independent study hours
Independent study 80

Teaching staff

Staff member Role
Timothy Brown Unit coordinator

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