Why does Christmas food make you sleepy? We ask an expert

Ahh Christmas. The one time of year when it’s socially acceptable to eat as much as you physically can and then crash out on the sofa for a little snooze.

But while it’s practically a tradition at this point for Christmas treats to put us into a food coma, here at Twisted, we were curious to find out the exact science behind it.

Registered nutritionist Rhiannon Lambert – who is also the Sunday Times best-selling author of The Science of Nutrition and host of the Food For Thought podcast – says that the sudden inclusion of mince pies, Christmas pudding and selection boxes have a big impact on our moods and energy levels – especially if we overindulge (guilty).

Rhiannon explains why Christmas food makes us sleepy. (Credit: Alamy)

“If we eat lots of refined carbs such as those found in classic Christmas food, we see a big spike in our blood sugar levels. This causes the pancreas to release the hormone insulin as quickly as possible to help keep our blood glucose levels steady,” she explains.

“However, this can actually result in too much glucose being removed from the blood, which causes that “crash” in energy levels and leaves you feeling tired and fatigued.”

It’s not just sweet treats that leave us feeling sluggish, though, as even your Christmas dinner could contribute to the sleepiness.

“A lot of meats, particularly poultry such as turkey and chicken, contain tryptophan which is an amino acid that promotes sleep,” Rhiannon says.

“To have this sedative effect, foods which contain this amino acid need to be consumed with a carbohydrate. This means that your Christmas dinner, with all the seasonal veg and meat centre pieces is the perfect combination for helping the body to produce hormones that cause us to feel sleepy.”

Rhiannon explains it’s better to have your favourite foods in moderation. (Credit: Alamy)

While Christmas food may leave us feeling lethargic, Rhiannon also says that it’s important not to restrict yourself at this time of year, and instead to enjoy your favourite treats in moderation.

“Balance is key, and eating what we enjoy helps to embrace a healthy way of living and a more positive relationship with food,” she advises. “So on top of eating our favourite foods, we’re making sure that we’re consuming a wide variety of carbs – particularly wholegrains – fruit and veg, protein, fibre, and healthy fats, as well as making sure that we’re staying hydrated.

“It’s not a bad thing to want to indulge on Christmas Day and giving yourself a break and enjoying being relaxed about what you’re eating and drinking can have huge benefits for our mental health!”

Rhiannon shared her top tips to combat drowsiness this Christmas. (Credit: Alamy)

However, if you do want to combat the drowsiness you feel throughout the day (and maybe manage to keep your eyes open for long enough to watch the King’s speech), Rhiannon has a few tips to help.

“When reaching for a snack, try to opt for foods that contain slow-releasing carbs, are higher in fibre and lower in sugars to help maintain steady blood sugar levels and to avoid feeling lethargic,” she recommends. “Why not have whole grain crackers for your cheese boards, a variety of mixed nuts instead of salty crisps, or dark chocolate squares instead of reaching for the selection box of chocs.

“Try to include more complex carbs in your meals, such as wholegrains and starchy vegetables like potatoes and parsnips, as these will help to maintain steady blood sugar levels, keep you energised and avoid the ‘blood sugar rollercoaster’ of sharp spikes and rapid drops.”

More potatoes? Sounds good to us.

Rhiannon can be found on Instagram, Twitter, TikTok, and via her website.