RecruitingObservational

Sex differences in interoception and mental health: an investigation across the menstrual cycle

Common mental health conditions like anxiety and depression affect men and women differently. Scientists believe this may be linked to 'interoception'—our ability to sense internal bodily signals, such as a beating heart or changes in breathing. Being aware of these signals plays an important role in how we manage our emotions. This study explores whether differences in sensing internal signals explain why mood disorders vary between sexes, and how natural monthly hormone shifts might influence these feelings. Men and women aged 18 to 40 living in the UK or EU can take part if they use an iPhone. Over seven months, volunteers will use a mobile app to log their daily mood, body awareness, and physical health. Some participants will also try simple perception exercises. Taking part helps researchers learn new ways to support emotional wellbeing.

At a glance

Status

Recruiting

Sponsor

University of Surrey

Enrolment target

624

Start

06 May 2025

Estimated completion

15 Dec 2026

Identifying sex differences in interoception (i.e. the perception of the internal state of the body), common mental health disorders (i.e. anxiety, depression) and mood, and somatic complaints (i.e. physical symptoms), and identifying whether the menstrual cycle may contribute to these differences.

What is this study about?

Every day, our bodies send quiet messages to our brain. These include a fluttering heart, a rumbling stomach, or changes in how fast we breathe. The ability to feel and recognise these internal signals is known as 'interoception'. Scientists now believe that tuning in to our bodies in this way plays a key part in how we recognise, process, and regulate our everyday emotions.

Conditions like anxiety and low mood are known to affect women more frequently than men, and the symptoms can feel quite different between the sexes. Past research suggests that men and women also differ in how accurately they detect their internal body signals. For women, natural hormonal changes across the menstrual cycle can also impact mood, but researchers do not yet know whether these hormone shifts change how the body senses internal signals.

This research project, run by the University of Surrey, aims to answer these questions. By tracking volunteers over seven months using a smartphone app, the team hopes to map how body perception changes over time and how it connects to mood. In the later stages, volunteers will test simple training exercises to see if learning to tune into bodily cues can directly improve emotional health.

Key takeaways

Explores how sensing internal body signals (like heartbeats) relates to mood and anxiety.
Open to men and women aged 18 to 40 living in the UK or EU.
Lasts around seven months and is mostly done via an iPhone app.
Investigates whether natural menstrual cycles influence how we feel internal body cues.
Tests whether simple body-awareness training can support emotional wellbeing.

Who may be eligible?

You may be eligible to take part if you are a man or woman aged 18 to 40, live in the UK or an EU country, and speak fluent English. Because the study uses a specialised tracking tool, you must own an Apple iPhone (iPhone 7 or newer) running iOS 13 or later. You should also have normal or corrected vision and hearing.

To keep the findings reliable and protect your safety, you cannot take part if you have a known heart condition, a neurological disorder, or if you have started or changed psychiatric medications within the last six months. The study is also not suitable for people with severe anxiety related to physical health symptoms, or anyone currently receiving gender-affirming hormone therapy or surgery.

Women taking part must not be pregnant, breastfeeding, or planning fertility treatment. To ensure clear results around natural cycles, women should not have a history of conditions such as thyroid problems, polycystic ovaries, endometriosis, or chronic lower tummy pain. Both naturally cycling women and those using hormonal contraception can join, but they will be placed into separate study groups.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged between 18 and 40 years old.
I live in the UK or an EU country and speak fluent English.
I own an iPhone 7 or newer running iOS 13 or above.
I do not have a known heart or neurological condition.
I have not started or changed any psychiatric medication in the last 6 months.
If female, I am not pregnant, breastfeeding, or dealing with chronic pelvic or thyroid issues.

Answer every question to see your result.

What does participation involve?

Taking part lasts around seven months in total and is mostly done from home using your iPhone. Each day and week, you will spend a few minutes on a mobile app answering quick questions about your mood, physical wellbeing, and body awareness (such as estimating your pulse). Women who have periods will also log their menstrual cycle.

After three months, some volunteers will be invited to attend a laboratory session to test how they notice sensations like breathing changes or heartbeats under controlled conditions. During the final two months, participants will be placed into groups to test different short daily training exercises on their phones, which may include simple thinking techniques or body-awareness tasks. You will receive updates about the study's progress throughout your time taking part.

Potential risks and benefits

You may find it rewarding to gain personal insights into your own health habits, and your answers will help scientists discover better ways to support mental health. The risks of taking part are low, though answering questions about mood and mental health can sometimes feel sensitive. The breathing tasks involve brief moments of mild resistance, and some lab tasks involve viewing emotionally charged images, but you are always in full control and will do practice trials first. You are free to skip any task or question, or stop taking part at any point, without having to give a reason and without losing compensation for the time you have completed.

Locations (3)

University of Surrey
Approximate
Guildford, England
Royal Holloway University of London
Approximate
Egham, England
University College London
Approximate
London, England

Common questions

Do I need to travel to a clinic or hospital?

Most of the study is completed entirely from home using your own iPhone. Only a smaller group of participants will be invited to attend an in-person laboratory session after three months.

Can I take part if I take the contraceptive pill?

Yes. Women who take hormonal contraception and women who have natural cycles are both welcome, but you will be placed into different groups so researchers can compare the results.

What happens during the breathing tests in the lab?

You will breathe through a mouthpiece that adds a small amount of resistance to test how well you notice the change. You will remain in control of your breathing at all times, and people with asthma or high health anxiety will not do this test.

What kind of phone do I need?

You must have an Apple iPhone 7 or newer, updated to iOS 13 or later, as the study app is currently only built for these devices.

Will I be paid for taking part?

Yes, volunteers receive payment for completing tasks up to the point they decide to finish or withdraw from the study.

How to find out more

Rosie Donaghy

r.donaghy@surrey.ac.uk - Official trial record

Always speak to your GP or specialist before deciding to take part in a study.