“On days when I take a long soak in the bath, I seem to fall asleep more easily.”
Have you ever noticed this?
It is tempting to think it is simply because your body warms up and relaxes, but changes in core body temperature play a big part in the relationship between bathing and sleep.
In fact, bathing and sleep have been studied, and research suggests that warming the body at the right time before bed may help you fall asleep.
So how warm should the water be, and how long should you soak?
As You Fall Asleep, Your Core Temperature Drops
Our body temperature is not the same all day.
Core body temperature, the temperature at the center of the body, follows a daily rhythm and gradually falls at night.
This drop in core body temperature is one of the physiological changes that take place as the body moves toward sleep.
What matters here is releasing heat from the body through the hands, feet and other areas.
You may notice that your hands and feet feel warm when you get sleepy. This is linked to increased blood flow to the extremities, which lets heat from inside the body escape.
In other words, sleep and body temperature are connected not so much by the idea that
“if you keep your body warm, you will sleep,”
but by the body releasing heat from within and the core body temperature falling.
Why Does Warming Up in the Bath Lead to Sleep?
This is where bathing helps.
When you soak in a bathtub, your skin warms up and blood flow to your hands, feet and other areas increases.
When you get out of the bath in that state, your body can release heat more easily.
You can picture it as a flow like this:
The bath warms your body
↓
Blood flow to the skin increases
↓
Your body releases heat after the bath
↓
Your core body temperature falls
↓
This supports the changes your body goes through on the way to sleep
That is the general idea.
So rather than rushing into the bath right before bed, the key is to leave time after bathing for your body temperature to change.
How Long Should You Soak? Guidelines From Research
In 2019, a research team including the University of Texas at Austin in the United States published a systematic review and meta-analysis of studies on bathing, showers and sleep.
It found that taking a bath or shower with water at around 40–42.5°C one to two hours before bedtime was associated with falling asleep faster and with better sleep efficiency, among other outcomes.
It also reported that benefits were seen even with a relatively short time of about 10 minutes.
So, as one guideline, you might start with:
• One to two hours before bedtime
• Aiming for 10 minutes or more
• A comfortable temperature of around 40°C
and see how it works for you.
Soaking longer does not mean better sleep.
Water that is too hot or a very long bath can also put a strain on the body, so it is important to keep it within a range that feels good.
Is a Half-Body Bath Good for Sleep, Too?
“Does it have to be a full bath, or will a half-body bath work?”
Some of you may be wondering.
A half-body bath, soaking up to around the waist, gives a gentler warming effect than a full bath, but lets you spend time slowly warming mainly the lower half of your body.
For that reason, it is one way to build a habit of warming up and relaxing at the end of the day.
However, the research introduced above did not look only at half-body baths.
That is why
we cannot go so far as to say that “a 10-minute half-body bath will improve your sleep quality.”
It is important to keep this in mind.
Rather than insisting on a half-body bath, we recommend choosing a way of bathing that you can comfortably keep up.
Once Your Body Is Warm, Rest Your Mind Next
Even if a bath has prepared your body for sleep, if you go straight from the tub to work emails, social media and videos, your mind may still be active.
After your bath, dim the lights a little.
Step away from your phone.
Listen to some quiet music.
Take your time.
You might also make your bath a signal that the day’s activities are over.
At La HEAD, in a calm, fully private room, we slowly care for not only your head but also your neck, shoulders and arms.
Precisely because we spend every day processing so much information, at the end of the day,
time to warm your body,
time to rest your mind,
and time to sleep well.
Try treating each of these as a little more precious.
Why not pay attention not only to how long you sleep, but also to how you spend the time before you fall asleep?
We look forward to welcoming you.