My HormonologyWonder why you splurge like a celebutante one week, buying stuff you don’t even need. Then on other weeks, you keep your wallet shut tighter than that annoying plastic electronics packaging, denying yourself even low-priced necessities in order to conserve your cash?

Research shows that the ups and downs of your monthly hormones can have a big influence on how much you spend and on what kind of items.

Here’s the spending style you can expect for each week of your cycle:

Week 1: Small stuff that adds up
Day 1 (onset of menstruation) to Day 7
Researchers found that you’re likely to fill your shopping cart with little items–like nail polish, flowers, books and magazines–as a way to distract yourself from period-related aches and fatigue. And, once your period is over, the spending doesn’t stop. Rising estrogen is boosting your mood and making you more optimistic about how much money you have to spend–a combination that makes you enjoy treating yourself even more.

Week 2: Your wallet is spring-loaded
Day 8 to ovulation (Day 14 in a 28-day cycle)
If you’ve got a budget to stick to, you better put your credit cards on ice. High estrogen and testosterone are ratcheting up your optimism and impulsiveness to cycle-long highs, making you more likely to buy–and buy big! Researchers also found that high estrogen makes you more prone to purchasing clothes, makeup and other products that that boost your beauty. You’re also more drawn to pricey name brands over lesser-known or generic brands during this week of your cycle.

Week 3: Pillows and pizza call your name
Begins day after ovulation and lasts 8 days (Day 15 to Day 22 in a 28-day cycle)
Your credit cards get a breather this week as rising progesterone coupled with lower levels of estrogen take down your confidence about your finances and make you a bit worried about how you’re going to pay all your bills. As a result, you may clip coupons, re-purpose items you already have or simply do without. However, your self-restraint may go out the window if see a pretty home decorative item or spot a delicious snack. Then, you’ll be willing to pay double just to have it! That’s progesterone’s influence. As this hormone rises, it brings out your urge to “nest” while upping your appetite, making more susceptible to blowing your budget in the home goods and baked goods aisles.

Week 4: Mood-boosters galore
Final 6 days of your cycle
Studies show that during your premenstrual Week 4, you’re prone to spending on items that give you a mood lift, for instance, renting a comedy, buying a toy you loved as a kid or treating yourself to a meal at a favorite restaurant. As the researchers explain, these self-soothing indulgences are a fast and easy way to temporarily counter irritability or the blues caused by plunging estrogen on these days, making a little splurge downright medicinal. However, keep your spending to a limit. The same plunging estrogen can trigger anxiety about reaching your financial goals. So, if you splash out money in a Week 2 kind of way, you could undo all the mood-lifting benefits you got from giving yourself a treat.

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