This might include health issues (your own or maybe a close family member) or other home issues. If you inform your College that you are having a hard time for whatever reason they may be able to help you with extensions, extended examination time, advice and information.
The University also understands that every case is individual and that is why they are not prescriptive about what constitutes a mitigating circumstance. It is always more difficult to apply mitigation after an event and the University will not normally allow this unless there are exceptional reasons for not alerting them to your situation before a piece of work is submitted or you have sat an exam.
Please consult your student handbook that is available on ELE as every University College has their own mitigation form and procedures.