Computer Science (Human Computer Interaction) (3 Years) [BSc]

Clocks, Sleep & the Rhythms of Life (E)

Unit code: BIOL31681
Credit Rating: 10
Unit level: Level 3
Teaching period(s): Semester 1
Offered by School of Biological Sciences
Available as a free choice unit?: N




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.


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 coordinate behaviour and physiology. You will cover a range of topics with a particular focus on how the neuronal basis for circadian timing in mammals and insects is regulated by the capture of environmental light by specific photoreceptors. The effect of light and daylength on season physiology is explored as well as the impact of circadian timing system on cognition and sleep.

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, from summer to winter.

•       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.

Employability skills

  • Analytical skillsStudents are encouraged to analyse the validity of conclusions of experiments presented during the lectures.
  • Oral communicationStudents are encouraged to answer questions during lectures.
  • ResearchStudents are directed to read primary literature in topics raised during the lectures and to independently search for new findings in those topics.
  • Written communicationEssay questions in examination.

Assessment methods

  • Other - 5%
  • Written exam - 95%

Assessment Further Information

2 hour written examination (95%) - choose 2 from 6 essay titles.

Other - elearning core multiple choice mid-semester test (5%)


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 and insect 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 signaling 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. To gain understanding of how the real world affects biological clocks, the effects of light and daylength on seasonal physiology are explored. Finally, the question of whether biological clocks deteriorate with age is addressed by investigation of the influence of lifespan on circadian rhythms in mammals.

Recommended reading

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

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.

Study hours

  • Assessment written exam - 2 hours
  • Lectures - 18 hours
  • Independent study hours - 80 hours

Teaching staff

Timothy Brown - Unit coordinator

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