We investigated whether it is possible to compensate for lack of sleep on some days with longer sleep on others, from a scientific point of view, despite the common belief that one can catch up on sleep on weekends or during vacation after stressful work days.
Lack of sleep can lead to various health issues. During sleep, the accumulation of beta-amyloids in the brain, associated with Alzheimer’s disease, is eliminated. Even just one night without sleep (31 hours) can result in a 5% increase in beta-amyloid levels in the brain. One day of sleep deprivation can be as detrimental to the body as consuming fast food for six months, causing decreased glucose tolerance and prediabetic conditions. Furthermore, it can result in psychological changes, including the inability to distinguish between neutral or friendly facial expressions of others, often interpreting them as threatening. Those who sleep less than six hours per night have a 20% higher risk of experiencing a heart attack, and they gain an average of 12.5 pounds (around 5.5 kg) per year. Scientists conduct numerous studies on sleep due to its significant impact on overall health.
Researchers in Sweden conducted one of the most extensive analyses to observe the effects of sleep on health. Over the course of 13 years, they evaluated the lifestyles of 43,880 volunteers by examining several parameters such as sleep duration, body mass index, smoking, physical activity level, and night shift work. The study revealed that individuals under 65 years of age who slept five hours or less per day experienced a 52% increased risk of death from all causes compared to those who slept seven hours. However, those who slept eight or more hours on weekends to catch up on sleep did not experience an increased risk and remained at the average level for the population.
However, inconsistent sleep durations on weekdays and weekends, coupled with varying bedtimes, can lead to social jet lag. While jet lag typically refers to the feeling of fatigue and unpleasant symptoms after experiencing a significant change in time zones due to air travel, it is also classified under code 7A65 in the International Classification of Diseases in the section on sleep-wake cycle disorders. In social jet lag, a person maintains a consistent sleep schedule on weekdays, such as going to bed at 10 pm and waking up at 6 am, but changes this routine arbitrarily on weekends, sleeping until noon after going to bed at 3 am. This disruption in sleep schedule is similar to crossing five time zones.
Social jetlag can pose a significant threat to the body. According to scientific calculations, every hour of difference between weekday and weekend bedtimes and wake-up times increases the likelihood of developing cardiovascular diseases by 11%. Furthermore, individuals under 61 years of age who experience social jetlag, which refers to the difference in the average number of hours of sleep on weekdays and weekends, are twice as likely to develop type II diabetes. Researchers in Brazil studying social jetlag found a connection between it and overweight and obesity. In Chicago, scientists analyzed the activity of American Twitter users and observed the time of posts with geotags, revealing that social jetlag correlates with excess weight. Moreover, social jetlag is associated with changes in blood indicators such as low levels of high-density lipoprotein (known as “bad” cholesterol), elevated levels of triglycerides (leading to the development of atherosclerosis and heart and vascular diseases), and higher levels of fasting plasma insulin and insulin resistance (potential indicators of diabetes development).
Jetlag affects not only humans but also the bacteria that reside in our gastrointestinal tract. Israeli scientists conducted experiments on mice and a small group of volunteers to study their gut microflora after a self-induced change in time zones. Although gut bacteria live in darkness their entire lives, the change in routine affected them. The bacteria responsible for food digestion became active at the wrong time, demanding to eat before sleep, while the “night-time” bacteria, responsible for restorative work and body cleansing, woke up during the day. Chronic jetlag in mice also led to the development of non-alcoholic fatty liver disease after three months, according to American scientists. This condition, in some cases, led to hepatocellular carcinoma, one of the types of liver cancer.
Swedish researchers discovered that catching up on sleep on weekends can reduce the risk of premature death, but excessive weekend sleep may cause health problems. Meanwhile, a team of scientists from the University of Colorado conducted a study with 36 volunteers between the ages of 18 and 39. They divided the participants into three groups: the first group was permitted to sleep for nine hours every night, the second group was limited to five hours of sleep, and the third group was only given five hours of rest for five days and allowed to sleep as much as they desired for the remaining two days.
During the nine-day experiment, both sleep-deprived groups gained an average of one kilogram in weight. Although the group that caught up on sleep over the weekend showed some health improvements, all of the benefits vanished once they returned to their five-hour sleep schedule. For instance, the group restricted to five hours of sleep experienced a 13% decrease in insulin sensitivity, while the group that caught up on lost sleep experienced a decrease ranging from 9% to 27%. One of the study’s authors, Kenneth Wright, a professor of integrative physiology and director of the Sleep and Chronobiology Laboratory, summarized the findings by stating that the “yo-yo life” of changes in eating times and circadian clocks on weekends, followed by insufficient sleep, is destructive in itself.
According to Michael Twery, director of the National Center on Sleep Disorders Research, frequently changing sleep schedules is a type of stress that is linked to metabolic anomalies. Scientists concede that prolonged weekend sleep may benefit those who do not regularly get enough sleep during the week, but only if it is done once a week. However, further research is required to investigate this idea.
Scientists suggest that maintaining a consistent sleep schedule with the same bedtime and wake-up time can help prevent many health problems. Prolonged weekend sleep cannot improve health that is compromised by consistent sleep deprivation during the week. However, if a person generally has a balanced sleep schedule and only occasionally experiences sleep deprivation during the week, sleeping in a little longer on weekends may be beneficial. Nonetheless, there is presently no experimental evidence to support the benefits of this approach.
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