“We better find out if people are having sex for 5 minutes.”

Dr Michal Kahn (we call her ‘Mika’) and I have been trying to answer a question.

If you have moderate-to-vigorous physical activity in the lead-up to bedtime - does it harm your sleep?

We’ve been analysing almost 200,000 nights of data recorded across the world.

We noticed a very small percentage of people are performing moderate-to-vigorous activity in the final hour before bed.

And the vast majority only spend up to 5 minutes being physically active.

I was thinking people might be squeezing-in some push-ups or stomach crunches.

But Mika raised a good point - people might be squeezing-in something else …

How Much For A Good Time?

I always like to delve into the scientific literature to investigate an idea.

So the first thing was to see whether having sex is considered to be moderate-to-vigorous physical activity.

The unit of measurement for physical activity is not ‘inches’ fellas - but METs - which stands for Metabolic Equivalent of Task.

One MET is the energy required to sit quietly (as opposed to sitting loudly…)

Moderate physical activities include:

• Walking briskly

• Mowing the lawn

• Vacuuming

And vigorous activity may be:

• Carrying a heavy load

• Shovelling

• A ball game (I can see these phrases used differently given this topic…)

So how much energy does it require to bonk?

One study showed that for women it’s 5.6 METs and for men it’s 6.0 METs. Fellas, it’s not a competition.

But is it a race?

How Long?

Guys, get your mind off ‘inches’ - this is about time.

How long do people take to have sex?

One study that used readings from couple’s armbands showed the duration lasted from 10 to 57 minutes - with the average amount of hanky panky taking 25 min.

For your interest - the beginning of sex has been defined as the beginning of foreplay until the orgasm and subsequent clean-up (I made that last part up).

But before we go too far… (too late!)

What happens when you ask people how long they spend bumping uglies?

60% say between 5-20 min. But back to our original question of whether some people shag for less than 5 min? A third of us do.

So Mika was right. It was possible that the moderate-to-vigorous activity we were seeing in the hour before bed may not be push-ups.

(I’m so glad this blog wasn’t written 9 blogs ago; hint: what’s the bus number in that picture above..)

It’s Business Time!

Since the 1970s, Dick Bootzin (that’s not the name on his birth certificate but that’s what he liked to be called) was recommending people to use the bedroom only for sex.

And sleep.

Actually, it was the other way round. Sleep and sex.

But does a bit of bedroom rodeo help you sleep?

You may have your own perceptions about whether rolling in the hay helps you sleep.

And you may not be alone. A survey of almost 800 people found that both men and women believe they sleep better after sex.

But these are just people’s perceptions. In other words these data come from people’s self-reports. If you’re a regular reader of our blogs, you’ll know the benefit of also getting data objectively.

And one of the best objective measures of sleep is polysomnography (eg, EEG).

Way back when Marty McFly was going Back To The Future, a group of researchers measured the sleep of 5 men and 5 women after they masturbated - with and without an orgasm. They also had a control condition where the participants read (Brisette et al., 1985).

These researchers found it didn’t matter whether the Big O happened or not - or if people were quietly reading or loudly not-reading - people slept the same.

To be honest, there is barely any research on the effects of sex on sleep.

There’s probably some good reasons for that.

As They Do In France

As a sleep scientist, you have to design studies where you manipulate a variable (in this case, ‘sex’ or ‘no I’ve got a headache’) and see if their effects on sleep are different.

And you need to do this while controlling for an array of other variables that can affect sleep (eg, lighting, substance use, other activities, etc.).

Notwithstanding having to order crates of tissues, a sleep lab is a good place to conduct such sleep experiments, because it helps to rule out the influence of other variables.

But then, it’s getting such a study through an ethics committee.

If you’ve seen an ethics committee - like I have - you’d wonder when these people last rogered.

But more seriously, consent to participate in research is necessary - and indeed in sex studies it would have to be well thought out.

Makes sense then that the only ones who have done this sort of study are French (have you watched their films?).

Is it Time for a Bit of Dick … Bootzin?

Technically, when Dick Bootzin - the inventor of Stimulus Control Therapy for Insomnia - was recommending people only use the bed for sleeping and sex, he intended this as a way for people to re-learn how to sleep.

After all, sleeping can be considered a skill.

So is it about time we recommend people with insomnia should be dancing in the sheets?

As we mentioned before, we’ve gotta be very careful about consent. You can’t see a client during one of your daily sessions and recommend that he goes home and wiggles the toothpick with his partner - well, except for this guy …

As much as researchers have recommended …

… that’s easier said than done.

Sex. Sleep. Repeat.

So far we’ve been focusing on the ‘Sex. Sleep’ part of this blog’s title. But now it’s time to ‘shift the gearstick’, and focus on the ‘Sleep. Repeat’ part.

What do we mean by this?

Well, can sleep affect your ability for ‘sexy time’?

The answer appears to be - yes.

Especially, if you have sleep apnea (ie, a sleep disorder where the person’s blowhole gets closed up and their breathing pauses).

A meta-analysis (ie, a powerful study that analyses the data from multiple studies) found that those with sleep apnea were more likely to experience an ED (Liu et al., 2015).

I thought ‘ED’ meant ‘Eating Disorder’ as the higher one’s BMI, the more severe one’s sleep apnea can be.

But it actually stands for (mind the pun) Erectile Dysfunction.

Conclusion?

The next time someone asks you whether sex helps you sleep - make sure you let them know that you’re already taken.

If they said they didn’t mean it that way - then let them know that there’s not enough scientific evidence - nor tissue boxes left on the shelf of supermarkets - for us to know if that is entirely true.

And for those who are inspired to progress our knowledge in this field, know that it may not be as easy as you think to recruit people to roll around in the hay.

According to Lei and South (that is seriously their names, not a euphemism for sex), their 2021 study states that sexual activity is on the decline.

Why?

Computer gaming, alcohol and greater difficulty forming relationships are the main reasons for those in the USA having less … sex.

Maybe we should leave this research up to the French - oui?

• Prof Michael Gradisar

Acknowledgement: I’d like to thank my wife for proof-reading this blog before it went to publication. It really needed it!

p.s. If you know how many euphemisms we used for the word ‘sex’ in this blog, then the first person to email us at hello@winksleep.online with the correct answer will receive a free copy of our e-book Sleep & Exercise.