Student study finds lower tryptophan intake linked to poorer sleep

A total of 11,485 students self-reported their sleep habits and diet, and the researchers used a food matrix to assess their tryptophan consumption before analyzing the results.

“These findings have important implications for nutritional recommendations aimed at enhancing tryptophan intake to improve sleep quality,” the researchers wrote in the journal Nutrients​.

They also pointed out that other social factors might be influencing students’ sleep, so more research is needed.

Growing sleep problems among young people​

Sleep is essential for our wellbeing, and lack of sleep has been linked to health problems like obesity, hypertension and impaired glucose metabolism​.

Studies show that sleep problems among young adults are increasing​, especially in university student populations. The researchers noted that university can be a time of great change for young people, which can affect their sleep. Studies have reported rates of up to 75% of university students declaring occasional sleep problems​.

Students tend to sacrifice sleep during the week to study and socialize before sleeping long hours on weekends​. Some also use caffeine, alcohol and other drugs, which can affect sleep.

This can all impact their quality of life. Lack of sleep has been associated with impaired concentration, reduced academic performance, impaired driving, risk-taking behavior, anxiety, depression, emotional instability, impaired memory and poorer health​.

Tryptophan essential amino acid, a precursor of serotonin and melatonin, is found in sources like beef and diary, nuts and wholegrains.

The large body of population studies to date demonstrates that tryptophan intake influences sleep duration by affecting the hypnotic neurotransmitters serotonin and melatonin​, however the research noted that before this study, most of the research focused on middle-aged or elderly adults.

Understanding student lifestyles​

This cross-sectional study was part of the uniHcos project, involving 11 Spanish universities. The project was launched to better understand the lifestyle habits of students entering university and how they change over time.

Study subjects included 11,485 first-year university students with an average age of 20. Women represented 72.7% of the overall sample.

Researchers used an online questionnaire to quiz students about their sleep. This included questions about how long they slept, sleep efficiency [whether they got the rest they needed] and any early waking and periods of insomnia. They also collected data on their diet to assess their tryptophan consumption.

Findings indicated that more than half of the students suffered sleep problems. This is higher than in other countries​. 

Tryptophan consumption was high. The researchers found median intakes were over twice the estimated daily requirement for both male (2.27 times) and female (2.60 times) students.

They also found that students who consumed the most dietary tryptophan had a reduced risk of sleep disorders compared to those in the lowest quartile. In addition, dietary tryptophan was positively associated with sleep duration, sleep efficiency and lower levels of insomnia.

“Our findings underscore the importance of moderately increasing tryptophan consumption to enhance sleep quality, particularly given that student intake exceeds current recommendations,” the researchers wrote. “Future studies should be carried out considering the large sample size, gender bias, other age groups and that other social factors may influence sleep quality.”

The study reported several limitations including gender distribution (which skewed towards women), the self-reported questionnaire format, the challenges of accurately calculating tryptophan intake and the use of the American food database despite the subjects consuming a Spanish diet.

The researchers also stated that sleep is complex and single factors like tryptophan intake might not tell the whole story.

Source: Nutrients​ 2024​, 16​(14), 2376
doi: 10.3390/nu16142376​
"Sleep Patterns and Tryptophan Consumption among Students at Spanish Universities: The Unihcos Project
Authors: Maria Morales-Suárez-Varela et al.