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Sleep & cognition

Can ear nerve stimulation help sleep-deprived soldiers stay alert?

Passi T, Närväinen J, Lukander K, et al. · Cognitive research: principles and implications · 2026

Open access · cc by · source: Europe PMC

Vagus nerve stimulation via the ear can help sleep-deprived individuals maintain their attention and mood during early morning hours when sleep pressure is highest.

Key findings

Overnight sleep deprivation generally increased reaction times and decreased positive mood. However, during the early morning hours, specifically at 5 am and 7 am, higher stimulation intensities were linked to faster reaction times on a visual attention task. Furthermore, higher stimulation levels were associated with a less severe decline in positive mood following the sleepless night.

Methodology

The researchers recruited a training group originally consisting of 50 special border Jaeger conscripts, with 48 participants completing the study. The sample of remaining participants was aged between 19 and 25. During a military field training program involving overnight sleep deprivation, participants received either active or sham electrical stimulation of the vagus nerve via an ear clip.

Limitations

Because the study evaluated only fit young male military conscripts, the findings cannot be easily generalized to women, older adults, or less physically active populations. Furthermore, the small group sizes add statistical uncertainty to the estimated benefits, and the lack of pre-experiment sleep tracking means individual baseline sleep quality could not be ruled out as an influence. Finally, because the nerve stimulation was only tested during a single overnight period, it remains unclear whether this method remains effective during chronic sleep restriction lasting multiple days.

How this study connects

Role on claims

Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.

  • Overnight sleep deprivation severely impairs basic alertness and attention, resulting in slower reaction times and significantly more attention lapses during simple vigilance tasks.

    Evidence for the claim as stated.

  • Transcutaneous auricular vagus nerve stimulation (taVNS) administered via an ear clip can help mitigate vigilance declines during early morning hours when sleep pressure is at its peak.

    Evidence for the claim as stated.

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