Bathing before bed is linked to falling asleep faster, sleeping for longer and sleeping more efficiently.
Having a bath or shower around 90 minutes before bedtime leads to the best sleep.
Bathing before bedtime is linked to falling asleep faster, sleeping for longer and sleeping more efficiently, studies show.
The best temperature for the bath or shower is between 104 and 109 degrees Fahrenheit (40-43 degrees Celsius).
Cooling the body’s core
Hot baths and showers work, slightly confusingly, because they end up lowering the body’s core temperature.
The hot water stimulates the thermoregulatory system, which causes blood to move from the core to the hands and feet.
This effectively cools the body’s core.
A cooling body temperature helps signal to the body and brain that it is time to sleep.
The reason is that our body temperature follows daily, or ‘circadian’, rhythms.
Body temperature naturally fluctuates by around 2-3 degrees and is at its highest in the late afternoon and early evening.
Around 90 minutes before bedtime, though, it is normally reduced by up to 1 degree.
The body’s lowest temperature is achieved through the middle and later parts of sleep.
Reviewing the research
The conclusions come from a review of 17 separate studies that examined the connection between taking a bath or shower before bedtime and sleep quality.
The results clearly showed the benefits of a hot shower or bath 1-2 hours before bedtime.
Shahab Haghayegh, the study’s first author, said:
“When we looked through all known studies, we noticed significant disparities in terms of the approaches and findings.
The only way to make an accurate determination of whether sleep can in fact be improved was to combine all the past data and look at it through a new lens.”
The study was published in the journal Sleep Medicine Reviews (Haghayegh et al., 2019).
