Scientists studied how artificial light at night affects Pacific field crickets and whether a natural supplement called melatonin could help. They found that nighttime light exposure during early development speeds up how fast young crickets grow, and it can harm their ability to reproduce as adults. The good news? Adding melatonin to the crickets’ diet helped restore their reproductive health. This research shows that the timing of light exposure matters—effects during early development are different from effects later on—and suggests that melatonin might be a way to protect animals living in our increasingly bright world.

The Quick Take

  • What they studied: Whether artificial light at night harms cricket reproduction and if melatonin (a natural chemical our bodies make) can fix that damage
  • Who participated: Pacific field crickets (Teleogryllus oceanicus) exposed to different lighting conditions during different life stages, with some receiving melatonin supplements
  • Key finding: Artificial light at night during early development sped up cricket growth and reduced their ability to have healthy babies, but melatonin supplements restored reproductive health in both males and females
  • What it means for you: While this study was on crickets, it suggests that artificial nighttime light may affect other animals’ health and reproduction. Melatonin supplementation appears promising as a protective strategy, though more research in other species is needed before applying these findings to humans or other animals

The Research Details

Researchers exposed young Pacific field crickets to artificial light at night during two different developmental periods: early development and late development. Some crickets received melatonin added to their food, while others did not. They then tracked how the crickets developed, grew, and reproduced as adults. This approach allowed scientists to see whether the timing of light exposure mattered and whether melatonin could reverse any negative effects.

The study was designed to mimic real-world conditions where animals living in cities or near human development experience varying amounts of artificial light depending on where they are and when they’re active. Rather than exposing all crickets to constant light their whole lives, the researchers tested what happens when light exposure occurs at specific life stages, which is more realistic for wild animals.

By measuring both male sperm health and female egg production, the researchers could determine whether melatonin’s protective effects worked the same way in both sexes and whether age played a role in how well the supplement worked.

Understanding when artificial light does the most damage is crucial because many animals experience changing light conditions as they move through different habitats or seasons. Previous studies often kept animals in constant conditions, which doesn’t reflect nature. This research shows that the life stage when an animal is exposed to artificial light matters tremendously—damage during early development has different effects than damage later on. This insight helps scientists better understand how to protect wildlife in our increasingly illuminated world.

This study was published in a peer-reviewed scientific journal (Proceedings. Biological sciences), meaning other experts reviewed the work before publication. The researchers used a controlled experimental design with different treatment groups, which is a strong approach for understanding cause-and-effect relationships. However, the study was conducted on one cricket species in laboratory conditions, so results may not apply equally to all animals or to wild populations. The specific sample sizes weren’t provided in the abstract, which limits our ability to assess statistical power.

What the Results Show

The research revealed that artificial light at night during early development (when crickets are young) accelerated their growth—they developed faster than crickets raised in normal light conditions. However, this early-stage light exposure also reduced the reproductive health of adult crickets, particularly affecting sperm viability in males and egg production in females.

When researchers gave crickets melatonin supplements, the supplement successfully restored reproductive function. Males who received melatonin had healthier sperm, and females produced more eggs daily. Importantly, the protective effect of melatonin appeared to work differently in males versus females, and possibly varied by age, suggesting that the supplement’s benefits depend on the sex and life stage of the animal.

Interestingly, artificial light at night during late development (after the early growth phase) did not produce the same negative effects on reproduction. This finding highlights that the timing of light exposure is critical—damage during early development has lasting consequences, while exposure later in development may not cause the same problems.

The study found that lifelong artificial light exposure did not affect total development time or adult body mass, meaning the overall size of the crickets wasn’t permanently changed. This suggests that while early light exposure speeds up initial growth, it doesn’t create permanently larger or smaller adults. The fact that melatonin’s protective effects were sex-specific and potentially age-specific indicates that males and females may respond differently to light stress and may benefit from different treatment approaches.

Previous research has shown that artificial light at night harms many animal species, but most studies exposed animals to constant light throughout their entire lives or focused on single life stages. This research advances our understanding by showing that life-stage-specific exposure matters—a finding that previous studies might have missed. The protective role of melatonin aligns with earlier research suggesting that artificial light suppresses melatonin production in animals, and that restoring melatonin levels can reverse some light-related damage.

The study was conducted on one species of cricket in laboratory conditions, so results may not apply to other animals or to wild populations experiencing natural environmental variation. The abstract doesn’t specify sample sizes, making it difficult to assess how confident we can be in the results. The research doesn’t explain exactly why melatonin works or what biological mechanisms are involved, only that it appears effective. Additionally, because this is a cricket study, we cannot directly apply these findings to humans without further research in other species.

The Bottom Line

Based on this research, melatonin supplementation appears promising (moderate confidence) for protecting reproductive health in animals exposed to artificial light at night, particularly when exposure occurs during early development. However, these findings are from crickets, and more research is needed before recommending melatonin supplements for other species or for humans. If you’re concerned about artificial light exposure, reducing unnecessary nighttime lighting remains the most evidence-based approach.

Wildlife managers and conservationists should pay attention to this research, as it suggests that protecting young animals from artificial light during critical developmental periods may be especially important. Pet owners with nocturnal animals might consider this research when managing lighting in their animals’ environments. Researchers studying other species should consider testing whether melatonin offers similar protective benefits. This research is less directly applicable to humans at this stage, though it adds to our understanding of how artificial light affects living organisms.

In the cricket study, melatonin’s protective effects on reproduction were measurable within the timeframe of the study (likely weeks to months for crickets). For other species with longer lifespans, benefits might take longer to observe. This research suggests that prevention during early development may be more effective than trying to reverse damage later, so protective measures should ideally begin early.

Want to Apply This Research?

  • If tracking light exposure, users could log daily hours of artificial light exposure after sunset and correlate this with energy levels, sleep quality, or mood over 2-4 week periods to identify personal patterns
  • Users could set a daily goal to reduce screen time 1-2 hours before bed and track compliance, while also noting any changes in sleep quality or daytime alertness
  • Establish a baseline of current nighttime light exposure (from screens, outdoor lights, etc.) and gradually reduce it over 4-8 weeks while tracking sleep metrics and energy levels to identify personal sensitivity to artificial light

This research was conducted on Pacific field crickets in laboratory conditions and may not apply directly to humans or other species. While melatonin is available as a supplement, anyone considering melatonin supplementation should consult with a healthcare provider first, as it may interact with medications and isn’t appropriate for everyone. This summary is for educational purposes and should not be considered medical advice. Always speak with a qualified healthcare professional before making changes to your health regimen based on animal research.