It’s a pretty common story. The sun has set. Labor starts to really kick in. Your contractions come closer and closer together. You race to the hospital, check in, thinking the big moment is right around the corner, and then… your labor stalls.
When it comes to stalled labor, often the blame falls on stress — the stress of the hospital, the stress of labor, the stress of impending parenthood. But another unexpected culprit may actually be responsible for stalling nighttime labor: Hospital lights.
Those eerily humming fluorescent lights beaming down on you in Labor & Delivery are not just unpleasant, they may actually slow down your labor’s progress.
You are more likely to go into labor at night.
As my doula once told me, our bodies prefer to labor at night, in the dark. Our primate kin prefer to labor at night as well. It’s fun to speculate that our ancestors on the African plains found night time labor safer, with fewer predators, but the exact why remains mysterious.
Whatever the true evolutionary reason, our modern bodies continue to maintain a nocturnal birth rhythm.
The uterus typically hits its stride in the late evening. Contractions tend to peak in intensity between 8:30 p.m. and 2:00 a.m., and labor itself most often begins between midnight and 5:00 a.m.
How does your uterine muscle know when the lights have gone out?
The short answer: Melatonin.
Our brains produce melatonin in the late evening into the night to regulate our sleep-wake cycle. But that’s not it’s only role. Melatonin also helps kickstart labor.
The body ramps up for labor well before the big day. Melatonin levels in the bloodstream start rising in the second half of pregnancy. (This seems hard to believe, given how elusive a full night’s rest can prove in your third trimester. But it’s true!) Then, in the last weeks before delivery, the uterus begins to sprout receptors for melatonin, making the uterine muscle sensitive to the melatonin floating through the bloodstream.
Even with both of these changes building up towards labor, melatonin on its own does not seem to directly induce labor. Oxytocin, the primary hormonal driver of labor, remains in charge. Melatonin instead seems to play the role of oxytocin’s wingman: potentiating the effects of oxytocin on the uterus and making oxytocin-driven contractions stronger and more effective.
If you expose a slice of uterine muscle in a petri dish to a low dose of oxytocin, for example, nothing will happen. But if you add some melatonin to the mix, the uterine muscle will begin to contract.
Thanks to melatonin, labor at night is more likely to stall when light interferes.
As you probably know from hearing ad nauseam about the dangers of screen time before bed — bright light, especially blue-green light, can suppress your brain’s production of melatonin. Suppressed production results in lower melatonin levels in the bloodstream following light exposure.
Are we messing with the natural rhythm and an evolutionary-tuned signal by basking in unnatural light in the middle of labor?
But does the “blue light effect” happen when a pregnant woman arrives at the hospital? Does the hospital lighting suppress melatonin and stall labor?
We can’t say for sure. (No one has directly researched how hospital lights affect labor.) But the circumstantial evidence points in that direction.
Light exposure at night has been shown to slow contractions, or even stop them altogether. A team out of the Florida State University has found that shining blue green light in a pregnant woman’s eyes at night will suppress contractions. The team is actually flipping this “problem” on its head by using blue-green light goggles to prevent preterm labor in high risk women. (We have some other concerns about this technology but we’ll save that for another post.)
How do you keep labor progressing at night?
In short, if your hope is to meet your baby ASAP, fluorescent hospital lights may not provide the best environment for that goal.
Fortunately, you can try a few strategies to get around the realities of our modern world: Labor at home for as long as you can, with the lights low. Pack candles in your labor bag (or even pick up some holiday lights!) and ask your care team to dim the overhead lights. Or, if you really want to take things up a notch, you could put some “blue blocker” glasses to the test.
Sure, you might look strange rushing into the hospital with your funky glasses and holiday lights but, trust me, how you look will be the last thing on your mind that night.
Read more about contractions at night and how you might be able to use your contraction patterns to spy on your body as it prepares for labor. Seriously, its pretty cool!