What Sleep Scientists Actually Want You to Do Before Bed

Most adults are doing their pre-bed routine wrong. Research published in the journal Sleep Medicine Reviews found that only 34 per cent of Australians consistently achieve the recommended seven to nine hours of sleep per night, and poor sleep hygiene — not stress alone — is the leading correctable factor. The science on wind-down routines has sharpened considerably in the past three years, and the gap between what people actually do before bed and what the evidence recommends has never been more stark.

The timing matters. South Australia is currently deep in winter, with Adelaide's July sunsets arriving around 5.15 pm on North Terrace. Short days scramble the body's circadian rhythm more than most people appreciate. Reduced light exposure suppresses the natural melatonin surge that should begin roughly two hours before sleep, and screens — particularly the blue-spectrum light from phones held at close range — push that surge back further still. The result is a population lying awake in bed, then reaching for a device, then lying awake longer.

The 90-Minute Window That Changes Everything

Sleep scientists at institutions including Flinders University's Flinders Health and Medical Research Institute, based here in Adelaide at the Bedford Park campus, have spent more than a decade documenting what they call the "sleep pressure window" — the 90 minutes before your target sleep time when behavioural choices most strongly predict sleep quality. Their core finding is simple: the body needs a consistent, gradual cooldown, not an abrupt transition from activity to darkness.

The practical architecture of that window looks like this. At the 90-minute mark, dim overhead lighting and switch to lamps or warm-toned bulbs below 2700 Kelvin. At 60 minutes, stop work emails and social media — completely, not partially. At 30 minutes, begin a low-stimulus physical or sensory activity. Body temperature is the biological lever here: a drop of roughly 1 degree Celsius in core temperature signals sleep onset to the brain, which is why a warm shower taken 60 to 90 minutes before bed — counterintuitively — accelerates the process. The shower raises surface temperature; once you step out, heat dissipates rapidly and core temperature falls.

Adelaide's geography offers genuinely useful wind-down infrastructure that most residents aren't fully exploiting. An evening walk through the Adelaide Botanic Garden on North Terrace — the gates on the Plane Tree Drive entrance remain open until dusk — provides low-intensity movement and natural light that supports the circadian reset without overstimulating the nervous system. The garden's 51 hectares include the Bicentennial Conservatory route, which is well-lit and accessible even on cold nights. Alternatively, the Linear Park trail between Felixstow and Campbelltown offers a flat, low-traffic 4-kilometre stretch that requires no gear beyond a coat and takes about 40 minutes at a relaxed pace — exactly the duration sleep researchers flag as optimal for evening movement.

What to Eat, What to Skip, and When

The Central Market on Gouger Street stocks several foods with genuine sleep-relevant properties. Tart cherries — available dried from the King of Nuts stall — are one of the few whole foods with measurable melatonin content; a 30-gram handful consumed 90 minutes before bed showed a statistically significant improvement in sleep duration in a 2023 trial published in Nutrients. Magnesium-rich foods including pumpkin seeds and spinach also support the GABAergic pathways involved in sleep onset. What to avoid is equally well documented: alcohol, despite its sedative reputation, fragments sleep architecture from the second half of the night onward, and caffeine's half-life of five to six hours means a 3 pm flat white from a Rundle Street café is still half-strength in your bloodstream at 8 pm.

Cognitive habits matter as much as physical ones. Writing tomorrow's task list before beginning the wind-down window — not during it — has been shown in multiple trials to reduce the "constructive worry" that keeps people awake. Keep the list to five items maximum. A notebook on a kitchen bench works better than a phone app, because picking up the phone reintroduces the blue light problem and, worse, the algorithmic pull of notifications.

The 5.15 pm sunset this week is a reasonable external cue to start building the habit. Begin dimming lights at 8.30 pm, walk the Botanic Garden or a quiet stretch of Linear Park earlier in the evening, and treat the 90-minute window before bed as non-negotiable time. Anyone experiencing persistent insomnia or severe fatigue should speak with their GP or contact the Sleep Health Foundation's referral line before self-managing further.