Study the given information carefully and answer the given question. Following are the observations of an experiment on 'sleep and memory' conducted on 18 healthy young adults (ages 18 to 25) and 18 healthy older adults (ages 61 to 81).

A. The recall after 8 hours of sleep in younger adults was 65% more than that in the older adults.
B. Night-sleep had higher negative impact on all of the participants as compared to that of day sleep of equal duration.
C. If a given set' of words is memorised immediately before going to sleep, its recall after waking up was found to be better in younger adults than in the older adults.

Which of the following can be concluded from the given findings of the research ?
I. As per the experiment, there is some correlation between sleep and memory.
II. The part of brain involved in memory is more active during the day as compared to that during the night.
III. A sleep of more than 8 hours can improve the memory in older adults.
IV. Memorising something immediately after waking up from an 8-hour long sleep will yield better results than memorising before sleep.