Med Diet Linked with Better Sleep in University Students

University stu­dents fol­low­ing the Mediterranean diet expe­ri­enced improved over­all sleep qual­ity com­pared to their col­leagues who did not adhere to the diet, the results of a new study sug­gest.

Researchers in the United Arab Emirates fol­lowed a group of 503 stu­dents at the University of Sharjah for five months at the begin­ning of 2021.

In recent years, sleep qual­ity has decreased at ​“an alarm­ing rate” glob­ally, with exces­sive use of screens at night largely blamed. However, the researchers wanted to inves­ti­gate the less-stud­ied link between diet and sleep qual­ity.

Previous stud­ies have demon­strated that poor sleep qual­ity is asso­ci­ated with increased risk for obe­sity, type 2 dia­betes and car­dio­vas­cu­lar dis­ease. University stu­dents are among the pop­u­la­tion groups at the high­est risk for sleep dis­or­ders.

Researchers used the Mediterranean Diet Quality Index (KIDMED), the most widely used index to assess Mediterranean diet adher­ence among young peo­ple, to deter­mine that 54 per­cent of par­tic­i­pants had medium or high adher­ence while 46 per­cent reported low adher­ence.

The stu­dents also filled out an Arabic ver­sion of the Pittsburgh Sleep Quality Index (PSQI), a stan­dardly-used index among researchers that scores users on seven com­po­nents of sleep qual­ity.

Overall, 83 per­cent of stu­dents reported poor sleep qual­ity. An equal num­ber of stu­dents with medium or high MedDiet adher­ence and low adher­ence reported poor sleep qual­ity. However, two-thirds of stu­dents who reported bet­ter sleep qual­ity also reported medium or high MedDiet adher­ence.

“In-depth analy­sis revealed that stu­dents with good adher­ence to the MedDiet were more likely to have a good sleep qual­ity even after adjust­ment for age and sex,” the researchers wrote in the study.

“The regres­sion analy­sis also showed that those with good adher­ence to the MedDiet had a sig­nif­i­cant asso­ci­a­tion with bet­ter sub­jec­tive sleep qual­ity, less sleep latency [the time it takes to fall into a deep sleep], sleep dis­tur­bance and day­time dys­func­tion even after adjust­ment for age and sex,” they added.

While the researchers acknowl­edged that fur­ther work is required to con­firm and bet­ter under­stand why adher­ence to the Mediterranean diet is linked with bet­ter sleep qual­ity, they pro­posed a few hypothe­ses.

Previous stud­ies have demon­strated that sleep qual­ity is ​“strongly affected” by food quan­tity and qual­ity, espe­cially with foods that exac­er­bate and alle­vi­ate inflam­ma­tion.

“[The] anti-inflam­ma­tory poten­tial of the MedDiet may help to explain, in part, the strong pos­i­tive asso­ci­a­tion between the good adher­ence to the MedDiet and the reported good sleep qual­ity com­po­nents found among our study sam­ple,” the researchers wrote.

They added that wors­en­ing sleep qual­ity and increased inflam­ma­tion could cre­ate a vicious cycle.

“When the bod­ily inflam­ma­tory state is increased, the sleep qual­ity is wors­ened, and when sleep qual­ity is wors­ened, the inflam­ma­tory state becomes increased,” the researchers wrote.

The rela­tion­ship between sleep and inflam­ma­tion partly comes down to cytokine secre­tion. Inadequate sleep leads to increased cytokine secre­tion, which increases inflam­ma­tion. Higher lev­els of cytokines have been repeat­edly linked with sleep depri­va­tion.

“These pro-inflam­ma­tory cytokines are those con­sis­tently reported to be reduced in response to the long-term expo­sure and adher­ence to the MedDiet, as revealed by many reports,” the researchers wrote.

Along with low­er­ing inflam­ma­tion, the Mediterranean diet is also rich in fruits and veg­eta­bles that are good sources of mela­tonin. An increase in mela­tonin can improve sleep qual­ity and pre­vent some sleep dis­tur­bances.

Along with sleep qual­ity, the researchers also quizzed the stu­dents on their chrono­type – an individual’s inter­nal cir­ca­dian rhythm that plays a part in deter­min­ing whether they are a ​‘morn­ing per­son’ or ​‘night per­son.’

They found that stu­dents with a morn­ing­ness chrono­type – who wake up early, accom­plish their most impor­tant tasks in the morn­ing and go to bed early – were six times more likely to have medium or high adher­ence to the Mediterranean diet than the other two chrono­types.

As a result, 30 per­cent of stu­dents with the morn­ing­ness chrono­type reported high sleep qual­ity, while less than 11 per­cent of stu­dents with an evening­ness chrono­type reported high sleep qual­ity.

The researchers said fur­ther stud­ies inves­ti­gat­ing the rela­tion­ship of chrono­type on diet and sleep qual­ity is required before any con­clu­sions may be reached on these data points.

However, they said the study and its results were an impor­tant step in rais­ing the issue of nutri­tion and sleep among uni­ver­sity stu­dents.

“Improving the knowl­edge and atti­tude of the uni­ver­sity stu­dents toward their dietary and lifestyle behav­iors, and the sig­nif­i­cance of chrono­type in deter­min­ing their future dis­ease risk fac­tors are of piv­otal impor­tance,” the researchers wrote.

“Further long-term, con­trolled inter­ven­tion research works are war­ranted for more elab­o­ra­tion on the impact of chrono­type and dietary habits on sleep qual­ity,” they con­cluded.

• Frontiers in Nutrition