* You’re tired and drained but you just had to go to the supermarket. On entering you see the ice-cream counter at the corner. You are a very health conscious person and normally never buy ice-creams. But today you are not able to control yourself and buy one for yourself.

* You have been part of a rough board meeting. As a CEO you have been grilled on how you will grow your business by the board members. Your house is nearby and you are walking back home. You have been off caffeine due to medical reasons. Yet, on passing a Starbucks outlet, the aroma of coffee pulls you inside the store. You end up buying a café mocha.

* You are returning home after a long evening at work. You are hungry and enter a supermarket to get some spinach but land up buying a few other food items that you’d normally not have bought; you tell yourself you’ll consume it at some point.

* As a consultant, the day has been hectic and you have had to run a day-long workshop with the top management of your client firm. You are mentally tired at the end of the day. On the way home, you enter a store to get your watch which was under repair. A salesmen makes you an offer for an expensive designer watch. You get carried away by the salesperson’s talk and decide to buy the watch which you may wear once in a blue moon.

Have you ever wondered why these things happen to rational people who normally use their brains for decision making? If you closely look at all the above scenarios, you will find that in each case the individual was mentally tired. And when you’re very tired, your ability to make good judgement calls takes a hit.

When you are tired, distracted or hungry, don’t be surprised if you make poor choices or weak decisions.

A person may not be physically tired but still be mentally exhausted after a day of work, long meetings or even solving a bevy of tough math problems. He or she is in a state of what psychologists call “cognitive depletion.” This means you have little energy left to make quality decisions. And when this happens your self-control and self-regulation suffer. Self-regulation means being able to control your thoughts, actions and behaviours. However, when you are worn out and tired, you are distracted and are not able to muster up as much self-control as usual. You become more impulsive—whether it’s snapping at a loved one or buying something you don’t really need.

In 1998, noted psychologist Roy F. Baumeister in his famous chocolate and radish experiment asked one set of students to eat chocolate-chip cookies another set were told to resist the cookies and have radish. Then these people were given a puzzle to solve. Those who had consumed radishes gave up solving the puzzle, while those who had cookies continued.

Baumeister suggested that we have limited will power—hence the students who had radish did not have sufficient will power left to continue the puzzle. He also found that the energy that was used for self-control was also used during decision making. Hence after making decisions or doing strenuous cognitive work, people do poorly at self-control.

This is also called the “depletion theory” of self-regulation. What it means that if you have resisted from a temptation the whole day, you may struggle later on.

So what does it mean to us? It means when you are tired, distracted or hungry, don’t be surprised if you make poor choices or weak decisions.

So how to avoid these occurrences especially with your shopping?

Here are a few suggestions:

• isit a supermarket with a list
• When you are tired, avoid shopping that requires you to make a lot of choices.
• Don’t go shopping when you are hungry; eat something before going shopping to increase your glucose levels.
• Remind yourself before going the store that you will not make any impulse purchase.
• Don’t make important buying decisions when you are hungry or tired.
• Stipulate a specific amount that you will spend in a store.