Normally the infants and the older persons need more sleep than usual whereas the adult just needs the normal sleep but that should be quality sleep as sleep has a significant effect on memory and mood and that also leads to productivity at the workplace, creative thinking, problem-solving, planning and many other things life.
Memory which has deep-rooted relation with quality sleep, temporarily stores and manages information required for cognitive tasks such as learning, reasoning, and comprehension. Further, memory is critically involved in many higher cognitive functions, including intelligence, creative problem-solving, language, and action-planning. It plays a major role in how a person in general process, use, and remember information on day to day life.
Now coming to age- age is negatively related to the qualitative aspect of memory. In other words, it signifies how strong or how accurate the memory is. In that sequence, the older the person, the weaker and less precise the person's memory. In contrast, poor sleep quality and depressed mood are linked to a reduced likelihood of remembering a previously experienced event and that sets the "quantitative" aspect of functioning memory.
It is very likely that seniors are more likely to experience negative mood than younger adults. Poor sleep quality is also often associated with depressed mood. For the mind to work at its best, it is important that senior citizens ensure they have good sleep quality and be in a good mood. Similarly, for adult also it is essentially required, they may not need longer sleep, but they definitely need quality sleep, to ensure them in a good mood.
It is no secret that as we age, we lose certain physical and mental qualities. Although the physical ones are the most evident, some mental ones can become a problem. Let us take the case of memory. An older person can lose memory gradually, almost without realizing it. What's more, they may have a long-term memory (remembering things that happened many years ago) and forget the most immediate things. Sometimes age also interferes with the quality and quantity of sleep, so it's not uncommon to see that older people tend to sleep less than younger people. These days I read how adults used to get depressed more, not only because of stress, family, work, but also because we stop secreting with time many hormones such as endorphin, serotonin, dopamine and oxytocin which is the group of natural chemicals that make us happy. While it is true that there are studies done on the subject, we must take into account that many of these problems are the result of multiple factors and obviously as in any rule, there are exceptions