Stress activates the nervous system. Cortisol rises. The body stays alert. That's the threat response doing its job. The problem is that it doesn't always know when to stop.
When cortisol stays elevated into the evening, the body can't make the shift it needs to. Our temperature won't lower. The mind won't settle. Sleep stays close but just out of reach.
It's more widespread than most people realise. Calm's Snooze Report, which surveyed 9,500 adults across the US and UK, found that financial worry, anxiety and racing thoughts are the most common reasons people can't fall or stay asleep. Sleep scientist Dr Matthew Walker, professor of neuroscience at UC Berkeley and author of Why We Sleep, calls it the "wired but tired" state: the body is exhausted, but the stress response keeps it from switching off.
The instinct is to chase sleep harder. To try to control it. But that rarely works. Walker's argument is simple: sleep quality is built during the day, not forced at night. The better question isn't how to make sleep happen. It's what's in the way.
Five things that help find balance
1. Manage stress during the day, not just at night
The evening is too late to start. The body carries what the day leaves behind. A walk, time away from screens, even a few minutes of stillness mid-afternoon, can begin to lower cortisol before it has a chance to follow you to bed.
2. Write it down before you switch off
A mind that's still processing the day won't settle easily. Spending five minutes before bed writing down what's unresolved, what needs doing tomorrow, and what's been weighing on you, gives the brain somewhere to put it. It's a small act, but it signals that the day is done.
3. Cool the room
Deep sleep requires the body's core temperature to drop. A room that's too warm works against that process from the start. Somewhere between 16 and 18 degrees is where most people sleep best. It sounds simple because it is.
4. Look at what you're sleeping under
Synthetic materials trap heat and moisture through the night. Natural fibres, wool in particular, regulate temperature and respond to the body as it shifts between sleep cycles. If you're waking in the night feeling too warm, your bedding may be part of the reason.
5. Lengthen the exhale
When stress keeps the nervous system alert, breathing is one of the few direct routes back to calm. A longer exhale than inhale, four counts in, six or eight out, stimulates the vagus nerve and signals to the body that the threat has passed. It doesn't require anything. It just works.
Often, the answer is environmental. Small things, but they compound.
Natural fibres respond differently to synthetic ones. Wool and hemp regulate temperature, absorb moisture, and let the body settle into the kind of stable environment that deeper sleep needs. It's not a dramatic fix. It's a quieter one. But it works with the body rather than against it.
During periods of stress, that steadiness matters more than usual.
Sleep doesn't need to be forced or perfected. It needs the right conditions. And more often than not, that means taking something away rather than adding something in.