Sleep is not a separate compartment of your life. What you do between waking and bedtime feeds into it, and last night's sleep feeds into how today goes.
That two-way relationship is easy to miss. Someone sleeps badly, feels drained, drinks more coffee, moves less, and sleeps worse again. The loop is the problem, not any single habit in it.
This section looks at each factor and at how strong the evidence behind it is.
Caffeine's effect on sleep is well documented. It is cleared slowly enough that an afternoon coffee still has an effect for many people at bedtime. How much varies widely between individuals, partly for genetic reasons.
Alcohol is one of the clearest cases where perception and measurement disagree. It shortens time to fall asleep and consistently disrupts the second half of the night.
Exercise is linked with better sleep across many studies, though most of that work shows association rather than proving cause. The common warning against evening exercise is weaker than its popularity suggests, and several studies find no harm for most people.
Meal timing has a growing body of research behind it, but it is younger and less settled than the areas above. We report it as promising rather than established.
The link between short sleep and impaired attention, mood, and driving performance is robust and repeatedly reproduced.
Some of these patterns need more than an adjustment to your routine.
How sleep works, how much you need, and where to go next.
What the strongest behavioural evidence points to.
The habits and conditions worth getting right first.
Medical disclaimer
This article is for general information only. It is not medical advice, and it is not a substitute for diagnosis or treatment from a qualified healthcare professional. Do not start, stop, or change any medication, supplement, or treatment based on what you read here. If you have symptoms that concern you, contact a doctor. If your symptoms are severe or sudden, seek emergency care.