2011JAMA
Leproult & Van Cauter
10 healthy young men
One week of sleeping 5 hours a night cut daytime testosterone by 10–15%, similar to 10–15 years of ageing.
Find on PubMed ↗Research library · Hormones & inner health
Hormones: your body's messengers
Cortisol, insulin, testosterone, oestrogen, thyroid hormone and melatonin set your energy, mood, muscle and sleep. Everyday habits move them more than most people realise, and some changes with age deserve a proper medical check.
Good evidence−10–15%testosterone after one week of 5-hour nights in healthy young menLeproult 2011, JAMA
5.2kmen in TRAVERSE: testosterone for low levels didn't raise heart attacks or strokesLincoff 2023, NEJM
up to 75%of women get hot flushes around menopauseThe Menopause Society, 2022 statement
01
The basics
A slow, chemical messaging system
Hormones are chemical messages released by glands into your blood. Your brain's hypothalamus and pituitary act as control centres, sending signals to the thyroid, adrenal glands, ovaries and testes, which then send hormones to the rest of the body.
Many hormones follow a daily rhythm. Cortisol peaks 30–45 minutes after waking to get you going and falls through the day. Melatonin rises after dark to prepare you for sleep. Late nights, bright evening light and irregular schedules blur both curves.
Sex hormones change with age. Men's testosterone falls slowly from about 40, faster with belly fat and poor sleep. Women's oestrogen drops over a few years around menopause (average age 51), which can bring hot flushes, poor sleep, mood changes, and faster bone and heart changes.
Your daily hormone rhythm
Cortisol peaks soon after waking to get you going. Melatonin rises after dark to prepare you for sleep. Light timing keeps both on schedule.
02
How it works
How a hormone message travels
1
Brain sends a signal
The hypothalamus and pituitary sense what the body needs.
2
Gland releases hormone
Thyroid, adrenals, pancreas, ovaries or testes respond.
3
Travels in blood
The hormone reaches every organ within minutes.
4
Cells respond
Only cells with the matching receptor 'hear' the message.
03
Measure it
Tests worth asking about
- Thyroid (TSH): if you have tiredness, weight change, feeling cold or hot, or hair changes.
- Testosterone (men): a fasting morning test, repeated if low, plus symptoms (low sex drive, erection problems, fatigue). One low result isn't a diagnosis.
- Menopause: over 45 it's usually diagnosed from symptoms; blood tests are mainly useful when younger.
- Insulin and HbA1c: see the blood sugar page. Insulin resistance often comes years before high sugar.
Try your number
LowTypicalHigh
1001100
Morning test. Typical adult range about 264–916 ng/dL (CDC-harmonised). Divide by 28.8 for nmol/L. Diagnosis needs symptoms plus two low results.
04
What the research says
The key studies
2023NEJM
Lincoff et al. (TRAVERSE)
5,246 men aged 45–80
In men with low testosterone and heart risk, testosterone gel did not increase major heart events over about 3 years, though some side effects (such as atrial fibrillation) were more common.
Find on PubMed ↗2024JAMA
Manson et al.
Review of Women's Health Initiative trials
Menopause hormone therapy is reasonable for bothersome symptoms in healthy women under 60 or within 10 years of menopause, but isn't advised just to prevent disease.
Find on PubMed ↗2017NEJM
Stott et al. (TRUST)
737 adults over 65
Thyroid pills for mild (subclinical) underactive thyroid didn't improve symptoms or tiredness.
Find on PubMed ↗2013European Journal of Endocrinology
Corona et al.
24 studies
Weight loss raised testosterone in men with obesity, more so with larger weight loss.
Find on PubMed ↗05
Take action
Habits that keep hormones in balance
Sleep, light, muscle and waistline do more than any 'booster'.
- 1
Sleep 7–9 hours
Testosterone, growth hormone and appetite hormones all depend on it.
- 2
Bright light in the morning
Sets your cortisol peak early and melatonin on time at night.
- 3
Lift and move
Muscle makes you more sensitive to insulin and supports healthy testosterone.
- 4
Lose belly fat
Visceral fat turns testosterone into oestrogen and drives insulin resistance.
- 5
Talk about menopause
Hormone therapy and non-hormonal options are effective; ask early rather than putting up with symptoms.
- 6
Test, don't guess
Symptoms plus proper blood tests, not online quizzes or saliva kits.
06
Myth or fact
Common myths, checked
✕ Myth'Adrenal fatigue' explains tiredness.
✓ FactIt isn't a recognised condition; a systematic review found no evidence for it. Real causes include poor sleep, depression, anaemia and thyroid problems.
✕ MythTestosterone boosters work.
✓ FactMost over-the-counter boosters have little or no evidence and some contain hidden drugs.
✕ MythHormone therapy causes breast cancer in everyone.
✓ FactRisk depends on the type, timing and length of use. For many women under 60, benefits outweigh risks.
✕ MythSoy lowers men's testosterone.
✓ FactMeta-analyses of human studies find no effect at normal intakes.
07
Questions
Frequently asked
Should I test my cortisol?
Only if a doctor suspects a gland problem. Single cortisol tests swing a lot through the day.
What is perimenopause?
The 4–10 years before periods stop, when hormones fluctuate. Symptoms can start in the early 40s.
Can men have a 'menopause'?
Testosterone falls gradually, not suddenly. Low levels with symptoms can be treated after proper testing.
08
Sources
References and related topics
- Leproult & Van Cauter (2011). JAMA. 10 healthy young men. PubMed ↗
- Lincoff et al. (TRAVERSE) (2023). NEJM. 5,246 men aged 45–80. PubMed ↗
- Manson et al. (2024). JAMA. Review of Women's Health Initiative trials. PubMed ↗
- Stott et al. (TRUST) (2017). NEJM. 737 adults over 65. PubMed ↗
- Corona et al. (2013). European Journal of Endocrinology. 24 studies. PubMed ↗