Japanese student athletes' routine of early morning practices before class make them vulnerable to sleep disorders, new research led by the University of Tsukuba shows.
According to the research team's results, many people around the age of 20 have "nocturnal" internal clock settings, possibly making rising early for sports practice extremely tough. There are many school sports clubs that hold early morning practices, and the researchers concluded that they need to exercise restraint.
In 2016, the team asked 906 students (with an average age of 19.1) in physical education faculties at five universities including Tsukuba about their sleeping patterns. The researchers then examined the relationship between these patterns -- including the times the students got up and went to bed -- and daily activities.
The results showed that 421 of the students, or 46.5 percent, had symptoms consistent with sleep disorders, such as the inability to sleep properly at night and spells of extreme drowsiness during the day. Compared to students who woke up at 8 a.m. or later, the risk of developing a sleep disorder was 5.5 times greater among those who got up in the 5 o'clock hour or earlier. The risk was 3 times higher among subjects who rose during the 6 o'clock hour, and 1.8 times higher for those who woke up in the 7 o'clock hour.
The study furthermore showed that staying up late also increased the risk of sleep disorders, with students heading to bed in the midnight hour 2.5 times more likely to develop symptoms than those who went to bed in the 10 o'clock hour or earlier. The risk rose to 5.6 times for those who hit the sheets at 1 a.m. or later.
According to University of Tsukuba professor Fumi Takeda, humans' biological clock dictates that it is better to wake up later the younger a person is. As getting regular and high-quality sleep is essential to boosting competitive athletic performance, student athletes "need to not only improve their wake-up and sleeping times, but also devise ways to avoid early morning practices," Takeda commented.