What is melatonin, exactly?

What is melatonin?

Melatonin is a hormone naturally produced by the body in response to darkness. A control center in the hypothalamus handles signaling related to processes that make us feel sleepy or awake, and when it’s dark (and only when it’s dark), the control center tells the pineal gland to produce melatonin. Natural melatonin production decreases with age, and people who have trouble sleeping are typically low in melatonin.

Should I take a melatonin supplement?

Study results are mixed regarding the effectiveness of melatonin as a sleep aid, and for its use in the treatment of all sorts of other physical and mental issues. It’s recommended that if you try it, you use it as a short-term supplement, for up to two months. The most common side effects are daytime sleepiness, dizziness, and headaches; there have been no reports of overdoses or toxicity.

Warnings: Melatonin could interfere with lots of different medications, so talk to your doctor if you’re medicating. It is the only hormone approved for sale in the US, and it is sold as a supplement, so it’s not regulated. Choose commercial supplements made in a lab, as those made from animal sources could contain contaminants.



What’s the deal with fireflies?

Why do they flash?

Romance. Adult fireflies use flash patterns to identify members of same species and opposite sex. Females of two species have been shown to prefer males with higher flash rates and stronger flash intensity, but otherwise not much is known about the flash patterns.

How do they flash?

A chemical reaction in the firefly’s light organ causes bioluminescence when oxygen can reach the photocyte cells. The photocytes are deprived of oxygen by neighboring mitochondria, which consume all the oxygen present, leaving the light cells dark. When a nerve signal instructs cells to produce nitric oxide, the mitochondrial respiration is halted and the oxygen present is free to be used in the bioluminescence reaction.

(Fun fact: I was first introduced to mitochondria as a child in the book A Wind in the Door.)

What else is cool about fireflies?

  • There’s a place in the Smokies where a species called synchronous fireflies flash at the same time. It’s not known why they’re synchronous: it could be competitive — if I flash first, the girls will notice me; or it could be collaborative — if our group flashes together, we have a better chance of getting the girls’ attention. Here’s a video. It’s a little bit creepy. Peak flashing in the park is late May to mid June.
  • Adults fireflies only live about 21 days, and don’t eat.
  • One species has a bluish light.
  • Females flash too but don’t usually fly.

Fireflies and lightning bugs are the same critters. Which do you say? I say both, but probably more often use “lightning bug.”


Scientific American

National Park Service

Tufts Journal