Next time you can't sleep, it might help to nudge your partner or reach for the nightstand drawer. A new study has confirmed what many have already figured out – sexual activity just before bed can help you sleep better.

Researchers at Central Queensland University and Flinders University in Australia monitored the sleep quality of seven heterosexual couples for 11 consecutive nights. Each night before bedtime, they alternated between three conditions: solo masturbation, partnered sex, or no sexual activity.

Participants completed daily surveys about their sex and sleep, and their sleep quality was measured objectively by polysomnography headsets that record brain activity, movement, and breathing.

Unsurprisingly, on nights with some form of sexual activity, participants pushed back their bedtimes by up to half an hour – but this was offset by a greater sleep efficiency. They also tended to spend less time awake during the night. These results weren't biased by self-reporting, either – they came straight from the sleep-recording headsets.

Participants did self-report improvements in their readiness and motivation for the day after sexual activity. Using a 100-point scale, they reported feeling up to 5 points more motivated the day after a solo session, and 11 points more motivated after engaging in partnered sex.

There didn't seem to be any improvements in how quickly participants fell asleep or how long they slept, but the team led by sleep sport scientist Michele Lastella from Central Queensland University suspects this might be partly due to the very small sample size.

Participants immediately having to put on a headset and start a phone app to record their sleep could also be dimming the afterglow, Lastella and his colleagues speculate.

To truly tease out the clinical benefits, the researchers suggest that future work should involve larger sample sizes, a wider range of sexualities, and include individuals with sleep disorders, health conditions, and a broader age range.

They probably won't have trouble finding volunteers.