How stress, travel and illness affect your cycle

Your cycle is run from your brain, and your brain is very good at noticing when life is a lot. Stress, illness or not eating enough can all tell it "now is not a great time", and the cycle adjusts.

What is going on inside

The hypothalamus releases gnRH, which drives FSH and LH. Physical or emotional stress can dampen these signals. The usual result is that ovulation is delayed, which makes your period late. Because the luteal phase is fairly steady, a late ovulation usually means a late period. A 2024 systematic review of 41 studies found that most reported a link between psychological stress and irregular cycles, though the way studies measured both varied a lot. Not everyone's cycle reacts to stress.

Common culprits

• Stress and anxiety: the NHS lists both as causes of irregular and late periods.
• Weight change: losing or gaining a lot.
• Too much exercise: especially if you are not fuelling it.
• Illness: a fever or infection around the time you would ovulate.
• Travel: disrupted sleep and routine are commonly reported triggers, but good studies on jet lag specifically are limited.

When stress or low energy goes on for a long time, periods can stop altogether. This is called hypothalamic amenorrhoea. The Endocrine Society says it can cause bone loss, so it deserves proper support rather than waiting it out.