What Is the Best Time of Day to Have Sex?

 Illustration by Michael Byers

The best time to eat: When you're hungry. Exercise: When you can. Have sex: Um… whenever possible?

For most of us, life's practicalities determine when we do what. But for certain daily events, there may be an ideal time. " 'When' is the ultimate life hack," says sleep psychologist Michael Breus, author of The Power of  When. "Knowing when allows you to perform the 'what' and 'how' to your maximum potential."

According to mounting research, those optimal times are dictated by circadian rhythm — the body's 24-hour timekeeper, which regulates not only sleep but also body temperature, hormone levels, blood flow, and gut bacteria. This system has ebbs and flows, meaning that certain tasks done at certain hours will yield better results — for example, exercising when blood flow is high and stress hormones are low. What's more, aligning daily activities to their prime times can boost long-term health, says Kenneth Wright, director of the University of Colorado Sleep and Chronobiology Lab. "The more we can live in sync with this biological cycle," he says, "the better we feel." Here's what that means for your day, 

Early Morning: Think creatively. 

Creative thinking and grogginess go hand in hand, says creativity researcher Mareike Wieth. Why? You're not as able to focus or filter distractions when you're sleepy; your mind wanders. As a result, says Wieth, "You're better able to think outside the box." Breus adds that because the brain moves new information from short-term to long-term memory during the final hour of sleep, the moment you wake up is also one of the best times to brainstorm ideas; any new information you've learned is more readily available.

His advice: Leave a voice recorder on your nightstand and use it as soon as you wake up, so thoughts don't slip away.

Before  Breakfast: Sex.

A recent study of 18- to 51-year-olds found that most people have sex between 11 pm and 1 am. That's the worst possible time, even if you haven't had a few cocktails. Late at night, levels of sleep-inducing melatonin rise and testosterone is at its lowest. But while you sleep, testosterone levels start to climb, possibly to repair and build muscle for the coming day. When you wake up, testosterone levels are at their peak. Physiologically, this is when sex is your best bet. That's not always possible, Breus acknowledges. "But," he says, "I'd love for everyone to make a point of having Saturday-morning sex."

Midday: Eat.

After 3 p.m., the body grows more insulin-resistant, notes Wright. This can mean that instead of converting sugar to energy, it's stored as fat. Eating big meals earlier as often as you can is helpful for a waistline, too. One study of 420 dieters found that those who ate their largest meal before 3 pm lost 25 percent more weight than people who ate heaviest at dinner.

Between 4 PM And 7 PM: Work out.

Almost all of us exercise better during this window, when body temperature is higher, joints are supple, blood flow is enhanced, and the hormone cortisol (known to break down muscle tissue) is waning. That doesn't mean you should drop morning workouts; behaviorally speaking, there is value to exercising before the demands of the day unfold. But when you have a choice, try to work out later in the day.

Before Bed: Take your meds.

If you have a prescription for a drug labeled take one daily, chances are your doctor has advised you to take it before you fall asleep. Physiologically speaking, there's good reason. Cholesterol drugs like simvastatin, for example, work better before bed because that's when the liver also starts breaking down cholesterol, and the drugs can work in tandem with the body. Blood pressure pills may have maximum impact at night because some people with hypertension don't experience a natural dip in blood pressure when they sleep. There's even reason to take over-the-counter drugs that can cause stomach upset, like aspirin, right before bed: The side effect goes unnoticed when you're asleep.