- Researchers recommend having a hot bath to help you fall asleep sooner.
- According to one research, having a hot bath 90 minutes before bed might help people fall asleep faster.
- The hot water really changes your body’s core temperature, allowing you to sleep at a lower temperature.
- A reduction in temperature signals to the body that it is time to sleep.
Taking a hot bath before bedtime may improve your sleep, especially if the water temperature and timing are exactly right.
A study team lead by Shahab Haghayegh, a PhD candidate in The University of Texas at Austin’s department of biomedical engineering, undertook a systematic data analysis reviewing research that connected bathing, water temperature, and sleep quality. The researchers examined 5,322 papers and drew findings from around a dozen with sound methodology. The findings were reported in the journal Sleep Medicine Reviews.
Bathing one to two hours — preferably, 90 minutes — before bed in water at 104 to 109°F (40 to 43°C) did the trick in helping people achieve the greatest quality sleep, according to their findings. Bathing at such time and temperature might help you fall asleep 10 minutes faster than usual.
Their study looked at how body heat affects the capacity to fall asleep.
The findings included data on sleep onset latency, which is the time it takes to transition from full alertness to sleep; sleep efficiency, which is the amount of time spent asleep compared to the total amount of time spent in bed meant for sleep; and subjective sleep quality.
Understanding Sleep and Circadian Rhythms
A circadian clock regulates sleep and our body’s core temperature, according to medical study. In the late afternoon or early evening, your body temperature rises by two to three degrees. It is at its lowest during sleep.
The typical person’s body temperature drops by 0.5 to 1°F (.3 to.6°C) around night. It reaches its lowest point during the middle and late stages of the night’s sleep and begins to rise as we prepare to wake up.
A warm bath or shower, contrary to popular belief, activates the body’s thermoregulatory mechanism, promoting blood circulation from the central core to the peripheral regions of the hands and feet. This can aid in the removal of body heat and the reduction of body temperature.
The underlying concept of warm-water bathing at night is based on a drop in core body temperature, which triggers the pineal gland to produce melatonin. Dr. Michael Breus, a clinical psychologist and diplomate of the American Board of Sleep Medicine as well as a fellow of The American Academy of Sleep Medicine, noted that for most people, this happens between 10 p.m. and 11 p.m. at night.
“This varies depending on whether someone is an early riser, a night owl, or an insomniac,” he explained.
The rationale behind timed bathing is that once we elevate our body temperature over 100°F (38°C), it must drop. This simulates the natural reduction.
Breus observed that immersing the body in cold water causes the body temperature to decrease, causing it to enter a fight-or-flight reaction and become alert.
When you take that precisely timed hot shower or bath in the evening, soak for 10 minutes — the best period, according to Haghayegh.
The Fundamentals of Bathing
Baths have a distinct effect on the body than showers, according to Breus.
“First, because it is a stimulation that surrounds the body, it affects your body temperature more fast,” he explained. A bubble bath forms an insulating layer around the body, keeping it warm for longer. “Because you’re lying down, your body can rest in a different way,” he says.
According to Dr. Andrew Varga, a sleep medicine expert at The Mount Sinai Integrative Sleep Center, patients who wash in the mornings and have sleep concerns, particularly difficulty falling asleep, may find that an evening shower or bath is beneficial.
“It appears to be a quite acceptable and low-risk technique with some data to back it up,” Varga said. Aside from that, cognitive behavioral therapy is the gold standard for addressing sleep-onset disorders.
Just don’t bathe too close to sleep, since this may not provide your body enough time to chill and may have negative consequences, according to Dr. Jianghong Liu, a professor at the University of Pennsylvania School of Nursing.
Internally, Haghayegh’s team is developing a new mattress system based on the University of Texas’s proprietary Selective Thermal Stimulation technology. Skin sensors would be included in the mattress to modify the temperature so that it could maintain an individual’s ideal temperature throughout the night, either on demand or automatically.
According to a 2018 study on climate change and sleep quality, increased day temperatures can lead to higher night temperatures. Because temperature is important for sleep quality, the authors believe that mild changes caused by climate change can have an impact on sleep.