Effects of 10-day confinement on the immune system and psychological aspects in humans

Abstract

We investigated the changes in percentages of leukocyte subpopulations, natural killer (NK) cells, CD69-expressing lymphocytes, and psychological aspects in 10 subjects who participated in a 10-day confinement study. Suppression of lymphocyte proliferative reaction and changes in leukocyte distribution are known to occur in space. These responses are similar to those induced by psychological stress. Ground-based confinement studies are suitable for validating the effects of stress arising only due to confinement. Two groups, consisting of five male subjects (ages 20-27 yr, mean 22.8 yr) each, participated in a 10-day confinement study. Blood samples were taken once before, three times during, and once after the confinement and activated with an anti-CD2 agonistic antibody cocktail. The percentages of leukocyte subpopulations, NK (CD45(+)CD56+) cells, and activated lymphocytes (CD45(+)CD69+) were measured by flow cytometric assay. The face scale test was used to measure psychological aspects. The percentage of CD69+ lymphocytes decreased during the period of confinement. This was mostly caused by changes in the ratio between NK and non-NK lymphocytes. The face scale showed that the subjects' moods improved toward the postconfinement period. Consistent with the face scale, the percentages of innate immune cells, such as NK cells and granulocytes, increased during the postconfinement period. We concluded that the changes in the distribution of immune cells caused by stress plays an important role in suppression of proliferative reactivity. The observed physiological reactions were specific to the confined environment, and the stress caused by confinement plays a role in the immune changes observed in space.

What happens to mood, performance and sleep in a laboratory study with no sleep deprivation?

“…The most dramatically affected mood dimensions were happiness and depression, which were impaired relative to baseline for the entirety of the study protocol. While this study is one of the first to demonstrate a potential relationship between the laboratory environment and negative mood, this finding is in line with previous research that has indicated negative mood in response to environmental factors such as temperature, odor and confinement . While the laboratory was highly controlled in regards to temperature and cleanliness, confinement or other aspects of the laboratory environment, such as restricted access to sunlight and exercise, may have negatively influenced mood.…”

“…However, these sleep times represent a significant decline relative to participants' habitual sleep durations. Thus, these findings are consistent with those of previous research demonstrating that despite adequate sleep opportunity, participants may not obtain habitual sleep amounts in the laboratory environment . While reductions below habitual sleep time are associated with mood and performance impairment, it is difficult to determine whether the substantial impairments in waking function observed in the present study are a result of these minor changes in TST and SE.…”

“…There is a small body of research concerned with the effects of confinement on mood. Shimamiya and colleagues 6,7 isolated participants for 10 days in a dive simulation chamber approximately 34 m 2 in size and containing bunk beds and a desk. Negative mood change was noted in some, but not all, participants.…”

Whole body and regional body composition changes following 10-day hypoxic confinement and unloading–inactivity

“…In particular, the participants were confined for 10 days in a rather small confined area during all experimental campaigns. Although the majority of studies investigating the effects of confinement to date focused on the effects of long-term (>100 days) confinement on stress responses (Chouker et al 2002), it has also been demonstrated that even shorter confinements (i.e., 10 days) result in altered immune and psychological responses (Shimamiya et al 2004). However, as noted in Custaud et al (2004) the duration of the confinement seems to largely determine the subsequent outcome and shorter confinement periods (i.e., 10 days) do not likely result in significant changes in body weight and composition.…”

Progressive Adaptation in Physical Activity and Neuromuscular Performance during 520d Confinement

“…Confinement studies have to date examined psychosocial [1], biomedical [2], skilled motor [2], [3] and immune system [4] variables. Aside from the most common case of prolonged confinement, imprisonment, individuals are also confined as part of over-wintering in isolated regions of the Earth [5], military operations [3], [6] and ground based spaceflight operation simulation [1].…”