Effects of total sleep deprivation on performance in a manual spacecraft docking task

Abstract

Sleep deprivation and circadian rhythm disruptions are highly prevalent in shift workers, and also among astronauts. Resulting sleepiness can reduce cognitive performance, lead to catastrophic occupational events, and jeopardize space missions. We investigated whether 24 hours of total sleep deprivation would affect performance not only in the Psychomotor Vigilance Task (PVT), but also in a complex operational task, i.e. simulated manual spacecraft docking. Sixty-two healthy participants completed the manual docking simulation 6df and the PVT once after a night of total sleep deprivation and once after eight hours of scheduled sleep in a counterbalanced order. We assessed the impact of sleep deprivation on docking as well as PVT performance and investigated if sustained attention is an essential component of operational performance after sleep loss. The results showed that docking accuracy decreased significantly after sleep deprivation in comparison to the control condition, but only at difficult task levels. PVT performance deteriorated under sleep deprivation. Participants with larger impairments in PVT response speed after sleep deprivation also showed larger impairments in docking accuracy. In conclusion, sleep deprivation led to impaired 6df performance, which was partly explained by impairments in sustained attention. Elevated motivation levels due to the novelty and attractiveness of the task may have helped participants to compensate for the effects of sleepiness at easier task levels. Continued testing of manual docking skills could be a useful tool both to detect sleep loss-related impairments and assess astronauts' readiness for duty during long-duration missions.

Fig. 1. Sleep deprivation study protocol.

All participants stayed in the laboratory for 5 days and completed two test sessions: one sleep deprivation condition and one control condition. The order of both conditions was counterbalanced and randomly assigned. The figure indicates the timing of scheduled sleep and test sessions for both groups.

Fig. 2. 6df manual docking simulation.

Spacecraft docking is based on the control of six degrees of freedom (a). Translation is controlled with the left hand control (joystick movement up-down and left-right, trigger movement forwards and backwards) (b), orientation with the right hand control (rotation of the joystick around its own axis for roll, movement of the joystick for pitch and yaw) (c). Screenshot of a level 4 6df docking trial showing the view from the spacecraft to the white space station (d). The black cross represents the target/docking port.

Fig. 3. Average docking accuracy scores under control and sleep deprivation conditions for each level of difficulty (each session started on level 4).

Error bars represent the standard error, the number of participants in each category is indicated above the bars. Dots show individual data points. Trials that were discontinued because the participant maneuvered out of the station’s reach (distance >200 m) were excluded.

Fig. 4. Average highest successfully completed 6df level per condition.

Dots depict individual data points; error bars indicate the standard error.