Do you have social jet lag? Rhythm, a new smartphone app, helps you understand your sleep rhythms

November 18, 2019

A free new smartphone application, Rhythm, developed by Dr. Yu-Hsuan Lin of the National Research Health Institutes, is a breakthrough for measuring sleep patterns that can help people improve their sleep health and consequently their overall quality of life. Its features represent an important advance over what current wearable devices can achieve.

It has long been recognized that sleep deprivation is harmful to mental health. Recent investigations, however, have shown that irregular sleep patterns — especially a pattern of regular sleep deprivation followed by increased weekend sleep time, or “social jet lag” — has an even greater adverse impact than sleep deprivation.

In order to help the citizens of Taiwan improve their overall health by managing their sleep patterns, the National Health Research Institutes asked Dr. Lin to develop a new app for smartphones. The application tracks smartphone-use patterns to derive sleep times and analyzes changes in sleep patterns. It has an accuracy of 90.4 percent for sleep-time estimation and a consistency of 87 percent for circadian rhythm fluctuation, demonstrating the app’s reliability. It also displays sleep patterns graphically, and notes how sleep patterns differ between weekdays and weekends, helping users avoid social jet lag. The research behind the building of this app was published in a top international journal, JMIR mHealth and uHealth, in May 2019.

Research at the National Health Research Institutes has shown that long-term irregular sleep patterns may increase the risk of not only diabetes and cardiovascular disease but also of cancer and mental illness. According to research published in JAMA Psychiatry, changes in activity levels and sleep patterns are a greater predictor of manic episodes compared to subjective mood changes. Sleep-pattern changes may be an important treatment marker for mania, depression, schizophrenia, and other mental illnesses.

Before the invention of this app, self-monitoring sleep patterns was difficult. Neither the wearable devices currently on the market nor in-hospital sleep laboratory investigation (i.e., polysomnography) can attain both accuracy and wide accessibility. In a one-month test of twenty-eight subjects, however, the Rhythm app achieved both high accuracy in its monitoring of sleep patterns (90.4 percent) and consistency (87 percent). The algorithm is able to accurately quantify weekend sleep times, which is a feature that wearable devices on the market do not have.

Certain occupations require early-morning starts, which may cause sleep deprivation and lead to catch-up sleep on the weekends, with late sleep times and late wake times. It is almost as if a person shifted one whole time zone from Taiwan to Bangkok on weekends and had to shift back on Monday. Research shows that social jet lag may increase the risk of obesity, diabetes, and cardiovascular diseases. In 2017, the American Sleep Association showed that one hour of social jet lag may increase the risk of cardiovascular disease by 11 percent. In 2019, an article in Current Biology showed that sleep deprivation may cause reduced insulin sensitivity and raised glucose levels, increasing the risk of diabetes. Social jet lag does not reverse the effects of sleep deprivation and may even worsen insulin sensitivity.

The free Mandarin-language app is available for Android phones at

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