(CNN) Are you having enough sex? You might have wondered if you should up your bedroom activity after reading about other couples' resolutions to have sex every day or about all the health benefits of getting horizontal .

In what might be welcome news for everyone exhausted from work and frazzled from kids, research suggests you don't have to get down every day to reap the rewards of sex, at least in terms of happiness and relationship closeness.

"I do think couples can end up feeling pressure to try to engage in sex as frequently as possible," said Amy Muise , a postdoctoral researcher studying sexual relationships at Dalhousie University in Canada. Once a week "is maybe a more realistic goal to set than thinking you have to have sex everyday and that feels overwhelming and you avoid it," said Muise, who is lead author of the study, which was published in November in the journal Social Psychological and Personality Science.

The study found that sex could boost happiness because it makes people feel more satisfied in their relationship, based on survey data from two separate cohorts, including 2,400 married couples in the U.S. National Survey of Families and Households.

"For people in relationships, their romantic relationship quality is one of the biggest predictors of their overall happiness," Muise said. "Having sex more than once a week might not be enhancing that (relationship connection), although it is not bad."

However, there are a couple of rubs with this research, Muise said. One is that it is not clear which came first, sex or happiness. It may be that people who have sex once a week or more were happier in their relationship and life to begin with, and not that the sex helped make them happy. Or both may be true: Sex enhances happiness and happiness enhances sex.

The other catch is that, although a weekly romp might be just what some people need, it might be too much or too little for others. "Certainly there are couples for whom having sex less frequently will be fine for their happiness, and there are couples who will get increases in happiness if they have sex more than once a week," Muise said.

What's the right number for you?

"One of the best effects of an article like this (by Muise and her colleagues) is that it opens up conversations with couples" about their sex life, said Vanessa Marin, a sex therapist based in Berlin. For some couples, the question of how often they should have sex might not have come up, which could be a sign they feel sufficiently close and satisfied -- or that they are just too busy or disconnected to think about it.

"Most couples want to be having more sex and I think this is really a result of how busy and full most of our lives are," Marin said.

Marin avoids prescribing an amount of sex that couples should have, because every couple is different, and instead recommends couples test it out for themselves. "I'm a big fan of having clients experiment, like, one month try to have sex twice a week and see how that goes, or once a week, try to play around with it," Marin said.

As for those lucky couples that are content with how often they get busy under the sheets, one study suggests they may not want to change a thing. Researchers asked couples that were having sex about six times a month to double down on getting down. Couples that doubled their sexual frequency were in worse moods and enjoyed sex less at the end of three months than couples who had stuck to their usual level of bedroom activity.

"Being told you should do something always makes it less fun," said George Loewenstein, a professor of economics and psychology at Carnegie Mellon University and lead author of the study. That is another reason Marin does not make recommendations to couples about sexual frequency -- for fear they could worry they are not living up to expectations and lose their mojo.

However, there's a far bigger relationship problem than couples worrying they aren't having quite enough sex -- "couples that have pretty much stopped having sex," Loewenstein said. For these couples, "I think once a week is a good final goal. ... It is almost like a natural constant to do it once a week," he said.

Even if these abstinent couples want to be having more sex, they may lack the desire for their partner. These couples can try conventional strategies, such as scheduling more quality time together or trying a change in scenery. "What couple has not had the experience that you go to a hotel in a new location in a new environment and the person you're with seems different, and different is good when it comes to sex," Loewenstein said.

But if these tricks aren't enough, couples may have to appeal to their rational rather than lustful side and tell themselves to just do it. "These couples might be surprised how enjoyable it would be if they restarted," Loewenstein said.

Should you schedule your sex?

It might sound like the least romantic thing in the world to pencil in sexy time with your partner. But if you and your partner are game to try, there is no reason not to make a sex schedule.

"For some couples, scheduling sex works really well, it gives them something to look forward to, they like the anticipation, they like feeling prioritized," Marin said. "Then other couples (say) scheduling sex feels horrible to them, like sex is transactional and just another item on their to-do list."

Again, Marin recommends couples experiment with scheduling sex to see if it helps them, as long as neither is opposed to it.

A good idea for all couples, whether they like the idea of scheduling sex, is to plan for quality time together -- just the two of them. Ideally, this would be about 20 minutes a day with the TV off and cell phones away, but for extra busy couples, it can help to reserve just five minutes a day for a tete-a-tete, Marin said. This time is also the "container for sex," the time and privacy when sex can be initiated, but you don't have to feel pressure about it, she added.

Although scheduling sex can help couples that want to be having sex but just can't find the time, it can make things worse for some. "If there are relationship issues or psychological issues such as stress or anxiety, then scheduling sex might just add to the pressure," said Acacia Parks, associate professor of psychology at Hiram College.

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As for when to schedule the sex, the best time is probably the time when you are least likely to be pulled away by life's obligations. One of the perks of rise-and-shine sex is that testosterone levels are highest in the morning, and this hormone drives sexual desire. On the other hand, tuck-you-in sex could help lull you to sleep, as hormones released during orgasm could help you relax and feel tired.

According to Muise, the participants in her research typically reported having sex at night before going to sleep, which is not that surprising. But it has to work for both parties. "This is another point of negotiation between partners," Muise said. "One of them is just too exhausted. That might be something to play around with, is there a time on the weekend that we could try instead."