Tiny living quarters only get love in mainstream science fiction unless there is a need to present a stressful or different setting. Too much of our space travel is shown on grand ships with lounges, hotel-sized quarters and gravity. The truth is, our first manned deep-space voyages are more likely to occur on ships designed like the ISS than the USS Enterprise. Can we thrive or even manage normal levels of stress in such conditions? Just the pictures of these apartments feel tight to me. Would we use such quarters to filter out individuals who would be unable to handle cramped living conditions during deep-space missions?

My response to tight spaces is pretty minimal. I've done quite a bit of spelunking, work in crawlspaces and such. But living in such tight quarters for months or years or, on the long side, a decade of spaceflight is a different matter altogether. I found an article outlining suicide rates in the military and it states the average for US military personnel is 10-13 per 100,000 with recent spikes nearly doubling that number to 22-23. This is a bit below the national average of almost 11 per 100,000. Sadly, submarine personnel, according to the same Strategypage article, is around 35 per 100,000. Around 3 times as high.

Submarine duty is the closest profession to that of deep space exploration, so the numbers are probably a good starting place. If the minimum viable population of a species is believed to be around 4100 individuals to provide a healthy DNA group, how many humans would need to leave on a 25 year flight to another planet?

If you sent 5000 people with an expected loss of 2-3 per year (50 suicides per year out of 100,000 = .0005 x 5000 = 2.5), you would only expect to lose only 50-75 personnel during the mission. But over 10 years, that could average 625 deaths. Leaving only 4375 - 275 beyond what is expected to be the viable minimum.

What if that number is higher? What if it starts low, at roughly submarine average, but follows an upwards trajectory with higher losses among family members with similar and unique DNA? Maybe 5000 is too low. If you're going to build a massive ship to ferry people across deep space, why not take 10,000 or even 25,000? 

Ignoring numbers, willingness to take on such an adventure isn't going to be enough. You can't have bodies dropping continually across the stars. Individuals with claustrophobia and other issues causing mental anguish to climb over time will need to be identified. Counseling will need to be provided. Anti-depressants will likely be included in every meal. 

Life on these flights will need to follow a military chain-of-command and be very dystopian.  Thoughts?

These Photos Of Tiny, Futuristic Japanese Apartments Show How Micro Micro-Apartments Can Be | Fastcoexist