Scientists have uncovered a biological cause of excessive daytime sleepiness in a breakthrough that could redefine understanding of the debilitating condition.
The condition—which increases the risk of diabetes, obesity and even heart disease—has long been dismissed as psychological, or the result of other sleep disorders.
But now sleep experts at Brigham and Women's Hospital, Boston, have identified seven molecules in the blood linked to excessive daytime sleepiness (EDS).
Writing in the journal eBioMedicine, they said their findings highlight the role of diet and hormones in daytime fatigue, revealing that omega-3 and omega-6 fatty acids may help protect against daytime drowsiness.
In the study, researchers collected data on 877 naturally occurring molecules in the body influenced by hormones and external factors like diet, known as metabolites.
After taking blood samples from 6,000 participants in the Hispanic Community Health Study and conducting a survey which assessed how often a person dozes off during the day in various scenarios, researchers pinpointed seven metabolites associated with the condition.
Dr Tariq Faquih, an expert in sleep disorders at the Brigham and Women's Hospital, said: 'Our study suggests diet and genetics may play an important role in EDS.
'As we learn what's happening biologically, we are beginning to understands why EDS occurs, the early signs that someone might have it, and what we can do to help patients.'
The team found omega-3 and omega-6 fatty acids—typically found in fatty fish, egg yolks and nuts—in particular were associated with a lower risk of daytime drowsiness.
Other metabolites such as tyramine, found in fermented and overripe foods, were conversely linked to an increased risk of excessive daytime sleepiness, particularly in men.
Tyramine was also associated with delayed and poorer sleep quality at night, which could exacerbate the effects of daytime sleepiness.
The researchers also identified three additional molecules that varied by sex—with hormones like progesterone associated with sleep-related processes like melatonin production.
They noted that whilst their results highlight potential treatment targets for EDS, including dietary changes, the study had some limitations and further research is needed to confirm their findings.
For example, sleep scores were assessed using a questionnaire, rather than lab tests which could have a confounding effect.
Additionally, they admitted it was difficult to determine the exact value of metabolites in the body.
Dr Faquid added: 'Conducting a clinical trial would be a big next step and could help us understand if omega-3s and omega-6s obtained from diet could help lower risk of EDS.'
EDS is thought to affect up to a third of people in the US, increasing the risk of heart disease, obesity and even death.
It comes as British researchers have suggested that omega fatty acids could help ward off Alzheimer's disease in women.
The scientists from King's College London and Queen Mary University London, discovered that women with the memory-robbing condition had significantly less healthy unsaturated fats in their blood.
Experts said the findings could indicate why more women are affected by the disease, and could pave the way for new treatments that highlight the crucial role lifestyle chances could play in the development of the disease.
