Whatever the reason, most of us have experienced a short or average night of sleep, and the ensuing next day foggy brain and fatigue.
And when tired, have you found the drive to tuck into sugared up or deep-fried junk food irresistible to deny?
Research has found sleep deprivation leads to impaired activity in the brain’s frontal lobe. This area manages complex decision-making. Simultaneously, when low on sleep, activity has been seen to increase in the deeper brain reward centres alongside the desire for more unhealthy foods when sleep deprived.1.
“What we have discovered is that high-level brain regions required for complex judgments and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified,” said Matthew Walker, senior author of a study published on the topic in Nature Communications.
Since, science has delved further in monitoring activity of the brain and found low-sleep can also affect our sensitivity to certain food smells, contributing to the drive for the junk.
Researchers from Northwestern University Feinberg School of Medicine tested a group of participants over two settings – ‘sleep-deprived’ getting broken sleep of around 4 hours, and several weeks later following a full a 8-hour sleep.2
Following each sleep, participants were asked to inhale “selected savoury and sweet high-caloric foods”2 (a.k.a junk food, like potato crisps and cinnamon buns) and non-food odours while having brain scans (fMRI) to measure the activity in certain areas of their noggins.
What did the researchers find?
“When tired, participants showed greater brain activity in two areas involved in olfaction—the piriform cortex and the orbitofrontal cortex—in response to food smells than they did when well rested,” study co-author Surabhi Bhutani told Science News. “That spike wasn’t seen in response to nonfood odors.”
It seems, then, this is another reason why we want the sugared up or deep fried junk food when tired – we become more sensitive to certain smells that can offer quick energy and feel-good rewards.
It’s amazing what biological drive can do to your resolve to steer clear of the cookies or chips. But it is not ideal when we have such ready access to these desired foods that are, in the end, more harmful than helpful.
So what to do?
Try to get your 7-8 hours of good quality sleep for much needed rest and repair to mitigate stress, illness, long-term health consequences (like type-2 diabetes), and be physically and mentally prepared for the coming day.
And if you waver and find you’ve inhaled a 6:30am Krispy Kreme, just make a more wholesome, nutritious and sustainable choice at your next meal.
By Angela Johnson (BHSc Nut. Med.)
- Greer, SM, Goldstein, AN, & Walker, MP 2013, ‘The impact of sleep deprivation on food desire in the human brain’, Nature Communications, vol. 4, p. 2259.
- Bhutani, S et al. 2017, ‘Central olfactory mechanisms underlying sleep-dependent changes in food processing’, The Journal of Cognitive Processing, [ePub ahead of print].