Complaints of excessive daytime sleepiness would have most doctors reaching for their referral pad to send the patient to the nearest sleep lab. However Australian research suggests another, more readily modifiable lifestyle factor might be to blame.

According to a large-scale epidemiological study, researchers from Flinders University determined a high intake of saturated fats and carbohydrates increases the risk of excessive daytime sleepiness.

And it’s not simply because a diet of hot chips and thickshakes will cause weight gain, and obesity is a well-known risk factor for sleepiness. In this study, they compared fats, carbohydrates and protein calorie for calorie – so it wasn’t how much you ate, or how energy-dense your food was – it was, in fact, the type of food you ate.