Short naps are good. Given modern workplace demands, this is not possible for many people - but if you have the option, try napping for ten to twenty minutes in the afternoon, preferably lying down in a darkened room.

It is unrealistic to want to be happy all the time.

My personal opinion is that the neutral position on the mood spectrum—what I called emotional sea level—is not happiness but rather contentment and the calm acceptance that is the goal of many kinds of spiritual practice.

Many exercise forms - aerobic, yoga, weights, walking and more - have been shown to benefit mood.

Dreaming is a phenomenon of purely individual consciousness, and consequently impossible to thoroughly deconstruct by a community of researchers. But dreaming matters.

Learning to focus attention and concentration is very useful; meditation can help you do that.

Low levels of vitamin D in the population as a whole suggest that most people need to take a vitamin D supplement. This may be especially true for seniors, as the ability to synthesize vitamin D in the skin declines with age.