Why sleep is scored first

The one activity that changes all the others

Every other score in Goodday assumes you showed up with a working brain. Sleep is what makes that true, which is why it is the one thing scored as a target rather than a rate.

The target is seven to nine hours. Sleep under seven or over nine both cost the day. That dip at both ends is deliberate - it comes from large population studies where both short and long sleep were linked with worse health outcomes (Hirshkowitz et al., Sleep Health, 2015; Cappuccio et al., Sleep, 2010).

Those studies show association, not proof. Sleeping eight hours does not guarantee a good day. But the pattern is consistent enough that Goodday treats sleep as the foundation of the score rather than one more line item.

Sleep is also the cheapest thing to fix

Two activities in the app are really about protecting tonight's sleep.

Morning daylight is worth +10 points per hour, up to an hour. Bright light early in the day helps anchor your body clock, which is the reason you feel sleepy at a sensible hour later (and it is associated with better mood).

Screens within an hour of bed are the most expensive thing in Goodday: -15 points per hour, up to an hour and a half. In one controlled study, people who used bright screens before bed took longer to fall asleep, felt less alert the next morning, and reported worse mood (Chang et al., PNAS, 2015).

That is a rare thing in wellbeing advice: an honest experiment, with a control group, showing a real effect. It is also the cheapest change in the app - a lamp, a book, and a phone in another room.

What to do with this

If your score is stuck and you cannot see why, look at sleep first. Then look at whether you got any daylight before lunchtime. Movement, connection and sea swims all score well, but they are hard to log honestly on four hours of sleep - and the score will tell you the truth about that.