London Summer IB Internships working hours

Hi everyone ! I'd like to apply for a 2018 BB summer internship in London. I noticed we could find a lot of useful information about how to succeed in the application process, but no one gives feedbacks on how the summer internship really unfolds, what is the most important part. Obviously everyone knows how challenging it is, but I'd like to know how hard are "living conditions" during these few weeks and especially regarding sleeping hours. I'm really seeking a summer internship that would respect a normal 7h sleeping time, and I'm ready to apply in a less prestigious bank if needed, so if anyone had more details on that very precise point ... Thank you all !