The latest wellness trend and “sleep hack” involves turning off the bathroom light before hopping in the shower.
In the dim light, the water seems to sound louder, the visual confusion of the day disappears and the hope is that sleep comes more easily.
This practice, often referred to as “dark showering“, or “shower in the dark”, has spread on social media, with some claiming that showering before bed in almost total darkness leads to better sleep. deep and fast.
There are few studies on showering in the dark as an isolated technique to improve sleep. However, sleep science is clear that 2 key factors that this ritual alters: light and heat. Both can nudge the body toward sleep or keep you alert.
Light is not just for seeingexplains Timothy Hearn, professor at the University of Cambridge, in an article on .
Bright light at night signals to the brain’s internal biological clock that it is still daytime. This delays the release of melatonina hormone that helps regulate sleep and is often described as the body’s “dark signal.”
In a 2010 study of 116 adults, typical bedroom lighting between dusk and bedtime reduced melatonin levels in the early evening by about 70% compared to very dim light. Exposure to ambient light before bed also shortened the total duration of melatonin release in about 90 minutes. Participants reported feeling more alert.
The bathrooms are often the brightest rooms of a house. Ceiling lighting and illuminated mirrors are designed for precision tasks that are useful in the morning but less useful in the evening. Turn these lights off, or dim them, removes a strong signal that it is still daytime.
In 2013, a exposed volunteers to typical bathroom lighting for just 30 minutes at bedtime. Melatonin levels went down and self-reported feelings of alertness increased even though participants remained in the bathroom.
Recent studies corroborate these results. One from 2025 compared bedtime exposure to cool white LED lighting with softer fluorescent lighting at the same intensity. The lighting increased time that took participants to fall asleep in about ten minutes and left them feeling less sleepy.
Another with teenagers, also last year, discovered that a burst of intense light in the early evening reduced melatonin levels three hours later and delayed the normal increase in drowsiness.
The same pattern appears in screen studies. A subsidiary that compared the reading on an electronic reader that emits light when reading a printed book discovered that the light device delayed the biological clockreduced melatonin and made it take longer to fall asleep.
One from 2023 that adjusted the “blue-weighted” impact of screens, i.e. the part of the light most likely to affect the biological clock, found that reducing this blue component decreased melatonin suppression and shortened the time needed to fall asleep.
I know showering in the dark replace time spent under bright lights from the bathroom or browsing on a cell phone, can help simply by reducing exposure to light at night.
The benefit will be less if the shower is followed by time under full lighting to dry your hair, choose clothes for the next day and tidy up.
Darkness also works gradually. Melatonin doesn’t activate instantly when the lights go out, and a brief shower won’t reset a body clock that’s been off for weeks.
Shower water can provide a second benefit. The investigation into passive body heatingwhich means warming the body without exercise, showed that a hot bath or shower taken at the right time can help people to fall asleep faster.
One from 2019 concluded that around 10 minutes in hot water one to two hours before bed shortens the time it takes to fall asleep in about 9 minutes and improved sleep efficiencythe proportion of time in bed actually spent sleeping.
Hot water dilates the blood vessels in the hands and feet, helping the body’s core temperature to drop afterwards, a key sign of drowsiness.
Showering in the dark can also help prepare the nervous system for sleep. In low light reduces the brain’s warning signals and makes it easier to transition from a state of alertness, often called the “fight or flight” response, to a calmer state of “rest and digest.”
In 2021, one asked volunteers to lie in a bathtub while sensors monitored their heartbeats. When the water was close to normal body temperature, about 37 to 38 degrees Celsius, the parasympathetic nervous system became more active.
This is the part of the nervous system that slows the heart and supports relaxation. THE heart rate has slowed slightly and heart rate variability has increased, a sign that the body is adapting and calming down.
A simpler one found a similar effect in 2025 using just hot foot baths. Young women who soaked their feet in hot water for ten minutes showed a increased vagal tone in 15 minutes.
Vagal tone refers to the signals carried by the vagus nervewhich helps regulate heart rate, breathing and relaxation. Higher vagal tone is linked to a more constant breathinglower levels of stress hormones and an easier transition to sleep.
Darkness supports the same process from another angle. Intense, blue-rich LED lighting can increase heart rate and reduce vagal tone within minutes.
A 2025 study found that dimmer, warmer lighting allows the heart rate variability increasessignaling a calmer nervous system.
Another factor is the sound of running water. One from 2024 found that natural sounds like rain or rivers flowing can lower cortisola stress hormone, and stabilize heart rate more effectively than silence. Warmth, darkness and soft background noise can therefore be combined to signal that it is safe to relax.
There are important caveats. No large trials have directly compared showers in the dark with showers in bright light by measuring objective sleep outcomes, so the idea is based on combination of related discoveries rather than direct evidence.
Furthermore, people with mobility difficulties may need some light to reduce the risk of slipping, and those who suffer from nighttime anxiety may feel uncomfortable in complete darkness.
As with most sleep advice, no isolated habit It is a cure for chronic insomnia. Light exposure during the day, timing of caffeine consumption, and stress management all play an important role.
