There are some days you just cannot resist the urge to indulge when someone offers you a free doughnut in the office. It might feel like your impulsive choices are arbitrary, but if you pay attention, there may actually be a clear pattern for which days you can’t control the cravings. According to new research, your self-control plummets the day after a sleepless night. Why? Stress.
In a new study published in the journal Personality and Social Psychology Bulletin, researchers asked 211 college undergraduates to complete an online survey every night for 30 days. In it, they were asked about things like how much they slept the night before, their alcohol use, the current day’s activities and events (for example, if they were having a conflict with a friend), and how stressful their day had been. The researchers also specifically tracked how much difficulty the participants were experiencing with self-control by having them either agree or disagree with three statements: “Right now my mind feels unfocused,” “Right now my mental energy is running low,” and “Right now I am having a hard time controlling my urges.”
“We found that after a night of shorter sleep than usual, participants reported having greater self-control difficulties than usual,” Garrett Hisler, a research assistant at Iowa State University and one of the study authors, explained.
Part of this effect was because sleep loss made the day more stressful than usual, which then increased self-control difficulties. “Thus, sleep loss both directly made self-control more difficult but also indirectly made self-control more difficult by increasing stress,” Hisler explained.
Basically, in addition to sleeplessness itself weakening your willpower, your self-control is further compromised because of exhaustion-induced stress, making it even harder to say no to your vice of choice. When you’re perceiving more stress, self-control feels way more difficult, leading you to make a variety of bad choices.
Just being aware of the relationship between sleep, stress, and self-control is beneficial and may encourage you to think your way through a self-control obstacle. However, the best thing you can do to avoid temptation altogether is get the right amount of sleep every night, which the Centers for Disease Control and Prevention estimates is “at least seven hours.”
“If you are on a diet and trying to resist the temptation of sugary foods, making sure you are getting enough sleep can be one way to reduce stress and increase the likelihood that you successfully resist their allure,” Hisler said.
If you are having trouble sleeping, there are several things you can do to combat insomnia, according to experts. Try shutting down any blue light sources—your phone, iPad, computer, the like—an hour before bed, keeping your thermostat between 62 and 80 degrees, and avoiding caffeine after noon. You’ll start to feel your impulse control kicking back into gear in no time.