Cortisol and melatonin tend to move in opposite directions across the day. Cortisol peaks soon after you wake and slowly falls; melatonin rises in the evening as it gets dark. That's part of the reason an argument or a stressful email right before bed makes sleep so much harder.
The Sympathetic Override#
Melatonin opens the door to sleep, but it doesn't push you through it. If your sympathetic nervous system (the "fight or flight" side) is highly active, your brain prioritizes staying alert over rest. Stress keeps your arousal system switched on, so you can lie awake even while melatonin is rising.
That's why stress-related sleep trouble usually shows up as difficulty falling asleep: you're tired, the room is dark, your body clock says it's night, and your mind is still running the day.
Why Lying There Makes It Worse#
When you spend night after night awake and frustrated in bed, your brain starts to link the bed itself with worrying. Sleep specialists call this conditioned arousal. It's why some people feel sleepy on the sofa and wide awake the moment their head hits the pillow.
The fix is counterintuitive: if you've been awake for what feels like 20 minutes, get up, go somewhere dim and quiet, do something calm, and come back when you feel sleepy.
Breaking the Stress Cycle#
You can't order yourself to relax, but you can give your nervous system cues that it's safe to switch off.
- 1.Physiological Sighs: Take two quick inhales through the nose followed by a long, slow exhale through the mouth. In a month-long study, five minutes a day of this "cyclic sighing" improved mood and lowered breathing rate more than mindfulness meditation did (Balban et al. 2023, Cell Reports Medicine).
- 2.A Screen-Free Last Hour: Protect the last hour of your day from incoming information: email, news, work chat. For a stressed brain, what's on the screen often matters more than the light it gives off. Our 3-2-1 wind-down routine is one simple way to structure that hour.
- 3.Brain Dumping: Write tomorrow's tasks and worries down on paper. In one sleep-lab study, people who spent five minutes writing a specific to-do list before bed fell asleep faster than people who wrote about tasks they'd already finished (Scullin et al. 2018, Journal of Experimental Psychology: General).
- 4.A Short Relaxation Practice: A guided body scan or non-sleep deep rest session gives your mind something slow to follow instead of replaying the day.
Daytime Habits That Make Nights Easier#
Stress is only one input. A body clock that knows what time it is makes the evening slowdown stronger.
- Morning light: about 20 minutes outside in the morning (longer under heavy cloud) sharpens the difference between day and night for your clock. A window cuts most of the useful light. Never look directly at the sun.
- Caffeine timing: caffeine and stress hormones stack. There's no universal cutoff; for one average cup and an average metaboliser, caffeine takes roughly five hours to fall below 50 mg, longer if you had a bigger cup or clear it slowly. More in when to stop drinking coffee.
- A consistent wake time: getting up at roughly the same time, even after a bad night, builds steady sleep pressure for the next one.
ARC's wind-down notification is a cue to start that screen-free last hour, timed from your bedtime, and its caffeine cutoff makes sure a late coffee isn't adding to the problem.
When to Talk to a Doctor#
If you've struggled to sleep three or more nights a week for three months, talk to a doctor. CBT-I (cognitive behavioural therapy for insomnia) is the recommended first-line treatment and works better long-term than sleeping pills. If stress or anxiety is affecting your days as well as your nights, that's worth raising too.
ARC is a wellness app, not a medical device. If sleep problems persist, talk to a doctor.