The first three searches that I did were in CORE.

1. The time frame for the first search was between 2001 and 2020.  The keywords I used were “Space Travel”.  This search returned 9,566,031 articles.  3,702,995 were in English.  This told me that I needed to refine my search more.
2. The second search was for the same time period.  I used the same first two keywords and added “isolation”.  This time I got even more articles, 10,886,577 and 4,037,612 in English.
3. The third search was for the same period and used the keywords from 2 but added “mental health”.  I got 18,254,711 results and 5,257,009 English ones.

The next three searches I did were in Military and Government Collection.

1. The first search in this database was “space exploration” which returned 5184 results.
2. I added isolation and it cut the results to 10.
3. My third search was space colonization and returned 23 results.

 
Articles that seemed likely to be useful were:

1. Doyle, 2016, Travel, Space and Transformation:        This article came up in all of my searches in CORE.  I think it likely contains useful information.
2. Mason, Curl, Kearns, 2016, Domains and levels of physical activity are linked to mental health in deprived neighborhoods: a cross-sectional study:        This article may be useful in that it studies the effects of physical activity on mental health in areas that are deprived.  Since the current nature of space travel makes the quarters cramped and the accommodations austere this study may have something relevant to say on the topic.
3.  Pyne, 2007, The extraterrestrial Earth: Antarctica as analogue for space exploration:   This should have some interesting things to say about living in an extreme environment in confined spaces and isolation and how it affects a person.
4. Munévar, 2014, Space exploration and human survival:        This article looks like it may have some things to say about space travel and the tolls it can take on a person.