Shift work puts your body clock at war with your roster. Shifty's job is to take the shifts you enter and turn them into a practical daily plan — when to get light, have your last coffee, wind down, and sleep — grounded in decades of published circadian-rhythm research. This page explains how that works and where the evidence comes from.
1. Your alertness is driven by two processes. Sleep scientists describe sleepiness as the sum of sleep pressure (which builds the longer you're awake) and your circadian rhythm (a roughly 24-hour internal clock that runs whether you've slept or not). This is the classic "two-process model" of sleep regulation. Shifty's Body-Clock Energy curve is a visual estimate of these two forces combined across your day.
2. Light is your body clock's master switch. The timing of bright light reaching your eyes is the strongest signal that shifts your internal clock earlier or later. Getting this timing right — and knowing when to avoid light — is the single most powerful lever a shift worker has.
Body-Clock Energy curve. Alertness naturally dips to its lowest point in the early hours of the morning (around 4–6am for a day-adjusted person), has a smaller mid-afternoon dip, and picks up again in the evening. Shifty re-anchors this rhythm to your sleep timing, because for a shift worker these peaks and troughs move with your schedule — not the clock on the wall.
Sleep windows. How long and how well you sleep depends heavily on when in your body-clock cycle you sleep. This is why day-sleep after a night shift is short and broken — a finding established in landmark sleep research. Shifty times your recommended sleep block to your specific shift, and treats the day after your last night shift as a special recovery day.
Light timing ("get light" / "avoid light"). Light in the evening pushes your clock later; light in the morning pulls it earlier. For night shifts, that means seeking bright light during the shift and shielding your eyes from morning light on the way home — a mainstay of occupational sleep medicine.
Why we shift your schedule gradually. The human body clock naturally runs slightly longer than 24 hours, so it adjusts to a later schedule more easily than an earlier one — the same reason travelling west is easier than travelling east. Shifty moves your plan in comfortable daily steps and warns you when a change (like a morning shift straight after nights) is genuinely hard.
Caffeine cut-off. Caffeine stays active in your body for hours — research shows a dose even six hours before bed can measurably disrupt sleep. Shifty places your "last coffee" early enough that it's cleared before your target sleep.
Meal timing. Eating during your biological night is harder on your metabolism. Shifty nudges you away from a large meal right before day-sleep — without pretending you can avoid eating on shift.
Napping & recovery. Well-timed short naps — before a night shift, or during it — are proven to reduce fatigue and sharpen alertness. After your last night shift, a shorter morning sleep plus daytime light helps re-anchor you to a normal rhythm faster than sleeping all day.
The principles above are well established in the scientific literature. The exact numbers Shifty uses — the precise shape of the energy curve, how fast it shifts your schedule, the specific timings — are sensible settings built on that science, not a personalised medical measurement. People differ by chronotype, age, health and lifestyle, so Shifty's guidance is deliberately conservative and directional. Always adapt it to how you actually feel, and speak to a healthcare professional about anything medical — including melatonin, which in Australia is a regulated medicine.