Late-nighters more likely to experience nightmares

Recent research led by Yavuz Selvi of Yuzuncu Yil University in Turkey suggests a possible correlation between staying up late and an increased frequency of nightmares. However, more evidence is needed to support this conclusion.

This study was inspired by a previous online survey of nearly 4,000 people, which suggested a link between night owls and nightmares in women ages 20 and up.

Despite the fact that most people spend between a quarter and a third of their lives sleeping, scientists actually maintain a very limited understanding of sleep. As of now, there is a general consensus that during sleep one experiences accelerated growth and rejuvenation of various systems in the body. Detailed mechanisms are still under intense research.

Sleep can be divided into two broad categories: rapid eye movement (REM) and non-rapid eye movement (non-REM). The latter can be further categorized into three distinct stages — N1, N2 and N3 — each defined by a different type of brain wave.

N1, N2 and N3 states of sleep are characterized by theta waves, sleep spindles and delta waves, respectively. The three types of waves differ in their frequency ranges. In a normal sleep cycle, people usually spend 45-55 percent of their time in N2 stage sleep. N3 sleep is when many sleeping disorders present themselves, such as night terrors and sleepwalking.

REM sleep takes up approximately 20-25 percent of sleep time. It is characterized by rapid eye movements, which inspires its name. This is usually when the most vividly remembered dreams occur. Furthermore, REM sleep is essential in memory consolidation and neurodevelopment.

Selvi's study was conducted on 264 university students. The participants were asked to rate the frequency with which they experience nightmares on a scale from zero to four, with zero being never and four being always. Those who considered themselves evening-types rated on average a 2.10, while the morning-types averaged 1.23. According to the scientists, this is a significant difference between the two groups.

Previous studies have shown that individuals who are sleep deprived often enter N3 and REM sleep faster than average individuals, and tend to remain in REM sleep longer. This is offered as a possible explanation for the higher frequency of nightmares experienced by those who are sleep deprived, due to having to wake up early despite going to sleep late.

The results also suggest a possible connection between circadian rhythm, one's natural biological cycle, and nightmares. However, more evidence is needed to support this idea.

Furthermore, some authors of the study suggest that there may be an association between mood and sleep. The stress hormone cortisol normally peaks early in the morning before waking up. Perhaps the shift in sleep cycles in relation to cortisol levels leads to more nightmares.

Unfortunately, the study admits that it was difficult to differentiate between true night owls and those who are early birds forced to stay up late. True night owls work better at night and would prefer to stay up late, while early birds would rather sleep early and wake up early. Researchers offer the possibility of employing sleep diaries in future studies to address this problem.

Another future study includes exploring the differences between gender and nightmare frequency. Since men and women have different emotional systems, there may be a difference in nightmare experiences.

Despite the association found between night owls and frequency of nightmares, the mechanism and reasoning behind this finding remains largely a mystery.