TOKYO - Sleep scientist Masashi Yanagisawa, a professor at the University of Tsukuba, offers explanations to common sleep-related concerns gathered from people on the street. People’s question: Is it better for sleep to take a shower or soak in a bath?
A woman in her 50s said she usually takes showers but wonders whether soaking in a bath leads to deeper sleep, asking whether bathing in a tub helps people fall asleep more easily.
Yanagisawa said the better option is soaking in a bathtub. He recommends getting into bathwater at around 40 degrees Celsius, neither too hot nor too lukewarm, for about 10 to 15 minutes roughly one to two hours before bedtime. This slightly raises core body temperature, and as that temperature later falls, the body is more likely to enter sleep smoothly.
People’s question: How are dreams created?
A man in his 20s said he has a simple, almost childlike question about why people dream, adding that he often dreams when his sleep feels light and wonders how dreams are formed.
Yanagisawa explained that vivid dreams with clear stories and emotions occur during REM sleep. REM sleep is a mismatched state in which parts of the brain are almost awake, allowing dreams to occur. It is not shallow sleep, he said, but a distinct and very important form of deep sleep. Dreaming itself is not a bad thing, and having vivid dreams indicates that sufficient REM sleep, or deep sleep, is being achieved.
People’s question: Is it okay to sleep while listening to sounds?
A woman in her 20s said she cannot fall asleep unless she hears voices such as from the radio and asked whether this should be considered a sleep disorder.
Yanagisawa said many people cannot sleep without sound. For those who sleep better with music or radio, he advised incorporating it into a bedtime routine. However, he stressed that it must be set to turn off automatically after falling asleep, warning that leaving it on all night is not advisable.
How to deal with waking up at night or not being able to sleep at a fixed time?
Caster Mai Ide asked about dream interpretation and whether dreams reflect inner worries.
Yanagisawa said it is fine to say there is no such connection. However, he noted that negative dreams, such as forgetting something important, may function as mental rehearsal for situations that could realistically go wrong, potentially building stress resilience.
Former Japanese record holder in the women’s 100-meter hurdles, Asuka Terada, said that since having children, even small things cause her to wake up at night. She explained that her child is now 11, but she still wakes up even when the child moves slightly, a habit that began when the child was younger and often became ill.
Yanagisawa said it would be better for parents and children to sleep in separate rooms. While this may be emotionally difficult for mothers, he said it is healthier for both sides.
Caster Eriko Yoshimura said her work schedule prevents her from sleeping at fixed times and asked what she could do.
Yanagisawa acknowledged situations such as having to arrive at a studio at 1 a.m. He said that because people cannot sleep deeply during the daytime, those with irregular schedules should aim to compensate by increasing their total sleep time over 24 hours. He added that segmented sleep is acceptable and emphasized the importance of sleeping as much as possible whenever the opportunity arises.
Start by understanding your own sleep
Caster Takahiro Inoue said the key point seems to be first understanding one’s own sleep.
Yanagisawa said health is built on three pillars: diet, exercise, and sleep. Diet and exercise involve conscious actions while awake, but sleep occurs without awareness, making it difficult to assess. He stressed the importance of making sleep visible by using wearable devices such as rings or watches, or more precise brainwave-based measurement services, to better understand one’s own sleep patterns.
Source: TBS
