Does showering in the dark help improve sleep? Here’s what the science says

Social media has turned into a kind of teleshopping channel where almost everyone presents themselves as an expert. It’s become a breeding ground for health products and hacks — many of them unsupported by evidence or backed by evidence that is forced or taken out of context. With minimal effort, these tricks promise users better health and fixes for problems such as lack of sleep, a widespread issue that, according to recent data from the Centers for Disease Control and Prevention (CDC), affects around one in three U.S. adults.

The latest viral hack to address lack of sleep is taking nighttime showers in the dark. Advocates claim this can help people drift off faster and sleep more deeply. The reality, however, as explained by physiologist María José Martínez Madrid is that no specific studies have evaluated showering in the dark as a formal sleep intervention, and it is not included in clinical insomnia guidelines.

“What we do know is that two factors on their own — reducing light exposure at night and taking a warm shower before bed — can support rest," she says. “But the combination, as such, is more a social‑media reinterpretation than an intervention with solid scientific backing.”

Clinical neurophysiologist Anjana López, a member of the Spanish Sleep Society’s Insomnia Working Group, agrees. She notes, however, that taking these showers with low lighting may offer one benefit: it allows people to focus on other sensory cues, such as the smell of the soap or the sound of the water. “It can be a way of keeping attention in the present moment, avoiding daily worries and rumination, which could in turn help the body relax and, with that, improve sleep,” she says.

Sleep experts often recommend taking a warm shower during the summer months, when hot, tropical nights make it difficult to fall and stay asleep. But their recommendation can be applied year-round. A meta-analysis published in 2019 in the journal Sleep Medicine Reviews concluded that taking a warm bath (38-40ºC, 100-1004ºF-) for about 10 minutes, one or two hours before bedtime, reduced the time it took to fall asleep by approximately nine minutes and improved sleep efficiency — that is, the proportion of time actually spent asleep in bed.

“This promotes peripheral vasodilation, helping to lower core temperature, which is one of the physiological signals for falling asleep,” explains Anjana López. “It’s not magic, it’s thermoregulation,” adds María José Martínez Madrid, who warns against showers that are too hot or too cold, which can have the opposite effect. Hot showers can activate a person, while cold showers can increase alertness.

There are also studies that support the importance of gradually reducing light exposure to improve sleep and increase the production of melatonin, the sleep hormone. In fact, sleep medicine experts often recommend using warm, low-intensity lighting as the afternoon progresses and evening approaches, and avoiding electronic devices (computers, smartphones, tablets) for at least two hours before bedtime.

A 2010 study showed that white light, common in many homes, delayed the onset of melatonin secretion and reduced hormone levels by approximately 70% compared to those exposed to very dim light. Another study demonstrated that exposure to white bathroom light for just half an hour before bedtime decreased melatonin levels and increased alertness in participants.

A 2025 study led by researchers at the University of Zaragoza in Spain compared the effects of exposure to red light and blue light, which is emitted by cell phones and tablets. The result? Both types of light suppressed melatonin secretion during the first hour after exposure, but, after two hours, only blue light continued to suppress it, which, according to the authors, underscores “its disruptive effects on circadian health.” A similar result was obtained in another study that compared blue-enriched light with standard light. The former “caused significantly greater melatonin suppression.”

In other words, showering in the dark or with a low-intensity light makes perfect sense, because darkness is essential for the brain to begin producing melatonin. However, as María José Martínez points out, the process isn’t instantaneous: “Melatonin begins to rise gradually in sustained low-light conditions, not like a switch that flips on in five minutes.”

Therefore, according to the experts consulted, a shower in the dark would be of little use if, up until the minute before getting in the water, you’ve been exposed to very bright light all night. Nor would it be effective if, once the shower is over, the person is exposed to bright light again or, even worse, starts scrolling through Instagram or TikTok.

“There’s no point in taking a shower in the dark right before bed if we’ve spent the last two hours after dinner watching TV or using our phones. We need to prepare our bodies for rest, and that pre-sleep preparation takes time,” says Anjana López. Martínez shares this opinion, noting that 10 or 20 minutes in the water with low lighting can be helpful as part of a transition to sleep, “but it certainly doesn’t compensate for exposure to bright light or screens until the very last minute.”

Therefore, according to Martínez, these kinds of tricks are only truly effective if they are part of good overall sleep hygiene habits. “What’s important is not the isolated gesture, but the entire context of the nighttime routine. Sleep responds to patterns repeated over time, not to ‘micro-tricks,’” she concludes.

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