Assessment of physical exercise benefits on brain health for long-duration spaceflights

Poor sleep on the ISS remains one of the major factors, which affects negatively the performance and psychological resilience of astronauts. Several studies have demonstrated that sleep is severely disrupted during space flights, where factors such as microgravity, workload, noise, light and other environmental influences play a role [1,2]. Notably, sleep disturbances are also typical during preparation for space flights on Earth, as was observed during a 520-day high-fidelity ground simulation of a Mars mission where a decline in sleep quality or vigilance deficits were found in the majority of astronauts [3]. “Strategic napping” has been recommended as an effective strategy for maintaining performance in commercial aviation pilots, although the negative effects of so-called sleep inertia represents an important confound [4]. Therefore, the development of novel effective countermeasures for sleep loss, performance decrements and psychological deficits associated with space missions is needed.

An intriguing possibility, which has not been tested previously, is that the benefits of exercise for the brain can complement cognitive and psychological benefits provided by sleep. Exercise has several benefits for health and it is widely used as a prevention or treatment for many diverse diseases through enhancing the overall fitness or strengthening the cardio-vascular system. But scientific evidence suggests that exercise has also numerous benefits for mental and psychological health. Even though the long-term effects of exercise have been thoroughly investigated and are quite well understood, so far only few studies have looked at brain activity directly during or immediately after exercise. A thorough understanding of what happens precisely in the brain during exercise from a neurophysiologic point of view would enable us to design specific training schedules aimed at “manipulating” selectively brain activity in specific regions to achieve specific needed benefits.

A fascinating prospect is that some types of exercise could compensate for the lack of consolidated sleep during long-duration space missions enabling the preservation of optimal brain functioning. At the moment physical exercise is only obligatory to counter the effects of osteoporosis during weightlessness in space. However, using exercise in space may also lead to marked improvement of cognitive functions and psychological state, which are crucial during long-term flights. In order to tackle this question, we started collaboration with the research group of Prof. Vladyslav Vyazovskiy from the University of Oxford (UK). This group is set up to perform neurophysiological and behavioural experiments in laboratory rodents, using state-of-the-art electrophysiological techniques in freely-behaving mice and learning tasks. In the framework of our collaboration we are exploring the link between specific behaviours and associated activity of single neurons in the brain of awake mice and the amount and quality of subsequent sleep. The next step will be to understand how this knowledge can be transferred to humans and ultimately can be integrated into the astronauts’ training and daily activities to improve cognitive functions and psychological state during long-term space missions.

The Project

The ACT is investigating the effect of physical exercise on brain health in the framework of an Ariadna Project: Assessment of physical exercise benefits on brain health for long-duration spaceflights. The project is done in collaboration with the Sleep, Brain and Behaviour group at Oxford University (UK) and a Young Graduate Trainee, namely Jessica Gemignani, working on the spike sorting algorithms.

Literature

1. Barger L.K., Flynn-Evans E.E., Kubey A., Walsh L., Ronda J.M., Wang W., Wright K.P. and Czeisler C.A. (2014). "Prevalence of sleep deficiency and use of hypnotic drugs in astronauts before, during and after spaceflight: an observational study." Lancet Neurol 13, 904-912. (link)
2. Mallis M.M. and DeRoshia C.W. (2005). "Circadian rhythms, sleep and performance in space." Aviat Space Environ Med 76, B94-107. (link)
3. Basner M., Dinges D.F., Mollicone D., Ecker A., Jones C.W., Hyder E.C., Di Antonio A., Savelev I., Kan K., Goel N., et al. (2013). "Mars 520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing." Proc Natl Acad Sci U S A 110, 2635-2640. (link)
4. Hartzler B.M. (2014). "Fatigue on the flight deck: the consequences of sleep loss and the benefits of napping." Accid Anal Prev 62, 309-318. (link)

Outcome