3 Surprising Factors That Lead to Bad Decisions

By Vicki Santillano, DivineCaroline

Today, all of us will make hundreds of decisions that range from the simple (“What do I want for dinner?”) to the complex (“What do I want out of life?”). Choices big and small dictate the paths our lives take, a fact that usually overwhelms me into chronic indecisiveness. I often look at people ruled by their instincts and wonder how they learned to trust their guts without fear. However, decision making isn’t as black and white as I assumed. I always believed I lacked the decision making gene, but there are surprising outside factors that affect the process.

To Sleep, Perchance to Decide
One thing’s for sure–poor sleep quality makes for poor decision making. In a 2007 study at Duke University published in the journal SLEEP, researchers studying sleep-deprived gamblers found that they were more likely to make impulsive, risky decisions because they focused more on potential rewards than consequences. Another study, this one in 2006 at the University of Amsterdam, concluded that when it came to high-importance purchases (such as a car), people made better decisions unconsciously instead of thorough deliberation. Their study championed an idea that many people espouse–that sleeping on issues is the best way to reach a decision.

Some studies have challenged this notion. In 2008, volunteers at the University of New South Wales made choices based on one of three methods–instant decision making, unconscious decision making (the “sleeping on it” method), and mulling it over. Researchers concluded that those who deliberated made the best choices. A 2009 study published in the Journal of the American Medical Association found that people did worse on performance tests taken right after waking up, suggesting that sleep inertia negatively affects decision making. Whether sleeping on decisions is a good idea is debatable, but it’s clear that being sleepy does not a good decider make.

Related: What’s Your Sleep IQ?

An Argument for Between-Meal Snacking

I try not to do anything on an empty stomach, but that goes doubly for decision making. That cranky, ravenous state has never been conducive to good choices and recent research has coincided with my findings. A 2008 study conducted jointly by Cambridge University and UCLA and published in Science controlled the diets of twenty participants to alter their serotonin levels and asked them to play a game. The game involved one player offering to share a portion of money with another player. If both accepted the offer, both got at least some amount of money; if the offer was rejected, no one benefited.

Under normal conditions, people generally rejected offers under one third of the total portion about 50 percent of the time. But when their serotonin levels were lower, rejection percentage increased to 80. People were more likely to act aggressively and carelessly when lacking serotonin, the feel-good chemical our brains make from tryptophan, an amino acid only found in foods like poultry, dairy, nuts, bananas, and shellfish. So when people are between meals and hungry, serotonin levels dip and crankiness–and rash decision making–increases.

Related: Best Snacks to Boost Your Mood

Hormones Have a Say

We can control sleep and hunger, but some factors that affect decision making are simply biological. For instance, women have a monthly cycle during which their hormones fluctuate. Most of us know that it influences our skin, body shape, and even our cravings, but it also plays a part in the options we’re pulled toward when making a choice. At the UK’s Aston University in 2007, thirteen women not under hormone-influencing medication were asked to give job packages of varying statuses to dominant- and non-dominant-looking men. The study found that certain stages of women’s cycles affected who they gave job packages to. For instance, those in the follicular (first) phase favored the dominant men. Other research has suggested that women view faces differently depending on cycle stages as well.

Men’s hormones fluctuate and affect their decision making abilities as well. Cambridge University professors John Coates and Joe Herbert performed a study that tested seventeen traders’ testosterone levels and compared them to their work results. They found that those who made money in the morning experienced a testosterone surge that ultimately led to risky, bad decisions. Coates and Herbert theorized that the increased testosterone in the morning fueled their desire to take chances and act aggressively, which had a negative impact on their performance for the rest of the day.

As an indecisive person who strives to overcome that label, I know that there are some things I do–like asking multiple people for advice–and some things I don’t do, like follow my gut–that lead to a struggle with choice. But there’s some comfort in knowing that there are actions I can take toward making better decisions, like getting enough sleep and eating right. Although, it’s nice to know I can pin the blame on factors beyond my reach every once in a while. (It’s not me, it’s my cycle!) That won’t make me a better decider, but it may ease the guilt from time to time.

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LMj Sunshine

Thank you for info.

LMj Sunshine

Thank you for info.

New G.
New G.3 years ago

Thanks for the information.

jane richmond
jane richmond4 years ago


Melanie Clark
Melanie Clark4 years ago

Now, I know why I'm so indecisive when I'm on my period. I have noticed this a lot lately, but it might also have something to do with my sleep pattern. Having 2 little ones, both under age 5 years, has made me sleepier, especially when the youngest one (14 months old) wakes me up in the middle of the night. So, I guess, that I can blame this on both. Thanks for the article! Very interesting.

Jay Evas
Jay Evas4 years ago

old news, what a waste of money that could have been spent studying something we didn't already know.

Jewels S.
Jewels S.4 years ago


Sarah Zemke
Sarah Z.4 years ago

Thank you!

Ivy D.
Ivy D.4 years ago


Conserve Earth
Conserve Earth4 years ago

Very good article. i like it.