Can catching up on sleep after staying up late really make up for the lost sleep?

Nowadays, staying up late seems to have become a normal part of life for many young people. According to the "China Healthy Sleep Survey Report 2022", nearly three-quarters of Chinese people have faced sleep problems, and the young and middle-aged groups aged 19-35 are the high-risk groups for sleep disorders. Most young people only sleep for about 7 hours on average, and it will even gradually decrease with age. What's more prominent is that more than 40% of young people stay up until the early morning before falling asleep.

So, if you stay up until 2 a.m., but catch up on some sleep until 10 a.m., can you restore your energy? Or even if you take a long nap on the weekend, can you make up for the damage caused by staying up late?

Why is catching up on sleep useless?

A study conducted a one-year sleep and mood study on more than 2,100 newly employed doctors. During the first year of physician training, these doctors generally faced long, stressful and irregular work schedules, so their sleep was very irregular. The results showed that people with irregular sleep, even if they were able to make up for 8 hours of sleep sometimes, still showed mental health problems such as emotional instability and high depression scores, and there was no significant difference from those who were severely sleep deprived. This study shows that irregular work and rest schedules, even if they make up for the time by sleeping in, cannot make up for the damage caused by staying up late.

Why is this so? The reason is that sleep is not just a "time issue", it is a complex process composed of regularities and cycles. Every night, our brain goes through a sleep cycle of about 90 minutes, passing through light sleep, deep sleep and rapid eye movement (REM) sleep stages in sequence, and each cycle is repeated about 4-5 times. The deep sleep stage is essential for physical repair, while REM sleep helps integrate emotions and memories. When we stay up late, the distribution and timing of these sleep stages are disrupted, especially deep sleep and REM sleep, which may not reach enough time. Even if you sleep a little longer during the day, the arrangement of these sleep stages will not be perfectly restored to the normal cycle like natural sleep at night, which will affect the repair of the body and mind during sleep.

In addition, staying up late will also cause our biological clock to be "out of sync". The biological clock is a circadian rhythm controlled by the suprachiasmatic nucleus (SCN) in the brain. It has a cycle of about every 24 hours and is responsible for regulating physiological functions such as body temperature and hormone secretion. A normal biological clock helps us enter deep sleep at night and stay awake during the day. When we stay up late for a long time, the biological clock will gradually become chaotic. Although catching up on sleep can make up for some of the lost sleep time, it is difficult to effectively restore the natural circadian rhythm.

What happens if you have long-term irregular sleep?

Irregular sleep not only makes us feel tired, but also causes a series of negative effects. Studies have shown that long-term staying up late is closely related to a variety of health problems, including mood swings, anxiety and increased risk of depression. Studies have shown that irregular work and rest is closely related to high depression scores. Even if people who stay up late can make up for enough sleep on some nights, their emotions and mental health are still significantly affected.

Not only that, staying up late will also affect the brain's cognitive function. Data from the China Sleep Research Society show that for most people, 7-9 hours of sleep is more appropriate, while sleeping more than 10 hours may increase the risk of cognitive impairment. Irregular sleep will actually disrupt the biological clock, making it difficult for us to concentrate at work or study, slowing our reactions, causing memory loss, and even making more wrong judgments. In the long run, these problems may affect work performance and interpersonal relationships, further exacerbating psychological stress and emotional distress.

How to get rid of staying up late?

The most important thing to get rid of staying up late is to maintain a suitable sleep duration and a regular schedule. To this end, we can try the following three methods:

Reduce stimulation before bedtime

Try to avoid high-intensity activities or emotional fluctuations before going to bed, such as working, arguing, or watching overly intense movies. Reduce blue light stimulation before going to bed, such as mobile phones, computers and other screens, which helps the brain secrete melatonin and allows you to fall asleep faster.

Gradually adjust your sleep schedule

If you are used to staying up late, you can gradually advance your bedtime by 15-30 minutes every day until you adjust to a bedtime that suits you. This can avoid the discomfort caused by a sudden change in your schedule.

Exercise moderately and reduce caffeine intake

Moderate exercise during the day can help improve sleep quality at night, but strenuous exercise should be avoided before bedtime. Reducing caffeine intake in the afternoon and evening, including tea, coffee, and energy drinks, can also help avoid sleep disorders.

References

[1] Fang, Y., Forger, DB, Frank, E., Sen, S., & Goldstein, C. (2021). Day-to-day variability in sleep parameters and depression risk: aprospective cohort study of training physicians. NPJ digital medicine, 4(1),28.

[2] Lemola, S., Ledermann, T., & Friedman, EM (2013). Variability of sleep duration is related to subjective sleep quality and subjective well-being: an actigraphy study. PloS one, 8(8), e71292.

Author: ACC Psychology Reviewer: Yang Xiaoyang, Associate Professor, School of Psychology, Sichuan Normal University