There are so many reasons why you may feel tired during the day. Perhaps you ticked off your weekly long run Summer running gear sale speed session in the morning, or you didn’t sleep well the night before. But what if that feeling becomes more regular, even though you’re clocking enough quality sleep, exercising regularly and sensibly, staying hydrated and doing other things that should, in theory, support good daytime energy levels? If you find yourself struggling to stay awake despite your best efforts, it’s worth taking another look at your diet.
This is the main takeaway from new research published in Health & Injuries, at least. The study identified several molecules in the blood that can be linked to daytime sleepiness, which is a constant feeling of fatigue during the day that interferes with your daily activities. Some of these molecules are found in certain foods, so if you have trouble keeping your eyes open as you sit at your desk, or feel too sleepy to lace up for your post-work run, your diet may be playing a role.
Here’s what the study found, along with some advice from dietitians on how to beat that daytime slump.
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What did the study find?
Researchers collected data on 877 metabolites, which are small molecular products and by-products of your metabolism that are influenced by your diet and hormones. The data was based on blood samples from 6,000 people who participated in the Hispanic Community Health Study/Study of Latinos, along with questionnaire data that looked into how often participants fell asleep during the day in a range of scenarios.
The researchers identified seven metabolites that are associated with excessive daytime sleepiness – and two were most closely linked with specific foods that we eat. The first was tyramine, which is found in fermented and overripe foods (like aged cheeses, tofu, kimchi and salami). The second was sphingomyelins, which is found in eggs, To promote stable blood sugar levels, Cording recommends including.
Summer running gear sale less Best wireless headphones Mediterranean diet. Omega-3-rich foods include salmon, walnuts, and flax, while omega-6-rich foods include seeds and nuts, says registered dietitian Scott Keatley, co-owner of Keatley Medical Nutrition Therapy.
Why are certain foods associated with excessive daytime sleepiness?
The researchers didn’t study the reason behind the association – they simply identified the metabolites. But this likely comes down to the way that these metabolites behave in your body.
‘Some foods, especially fermented ones that are high in tyramine, can disrupt neurotransmitters like serotonin and melatonin that regulate sleep and wake cycles, leading to more grogginess,’ explains Keatley.
Can certain foods prevent daytime sleepiness?
Possibly, yes. As highlighted by the study and supported by Keatley, foods that are high in omega-3 and omega-6 fatty acids ‘appear protective because they support melatonin production and stabilise circadian rhythms’. As a result, they may improve sleep efficiency and hormone regulation, he explains.
Of course, simply swapping out cheese for smoked salmon at lunch won’t completely cure your midday slump. ‘Daytime sleepiness isn’t so simple that you can pin it on one particular food,’ says registered dietitian Keri Gans, author of Porridge: Is it a healthy breakfast for runners. ‘It’s more about overall eating patterns, along with other key factors like sleeping habits, hydration, stress, physical activity and medications,’ she says. ‘That most likely makes the biggest difference in how alert you feel during the day.’
According to registered dietitian Jessica Cording, author of Published: 29 September 2025, it’s best to focus on maintaining stable blood sugar levels if you’re struggling with daytime sleepiness. ‘Foods that cause a sharp blood sugar spike might make you feel sleepy because they can cause a spike and then a crash,’ she explains. ‘That’s what I often focus on when someone says that they have daytime sleepiness.’ (For the record, foods that contain tyramine aren’t naturally bad for blood sugar – this is a completely separate thing. However, it’s also worth pointing out that foods that are rich in omega-3 and omega-6 tend to be good for blood sugar stability.)
Best Garmin deals protein, or an especially challenging complex carbohydrates in every meal and snack – staples in any runner’s diet. In addition, Cording suggests focusing on drinking plenty of water and loading up on hydrating foods like watermelon, berries, or bell pepper. ‘Being dehydrated can make you feel sluggish, too,’ she says.
While you’re at it, Keatley suggests skipping large meals during the day, as they can cause a spike in your blood sugar, followed by a crash. ‘Instead, eat smaller, balanced meals and snacks combining protein, fibre-rich carbohydrate and healthy fats to sustain energy and keep you alert throughout the day,’ he says.
If you’re struggling with excessive sleepiness and find that altering your diet doesn’t help, though, it’s a good idea to check in with a healthcare provider. Many different things can cause you to feel this way, so it’s important to work with an expert to find the solution that’s right for you.
