Sleep guides
Clear explanations, based on sleep science, to understand and improve your nights.
How many hours of sleep do you need, by age?
Official sleep duration recommendations by age, explained: why needs change from infancy to your senior years, and what to do if you're falling short.
Understanding sleep cycles: the science behind the 90-minute rule
How 90-minute sleep cycles actually work, what happens in each stage, and why timing your wake-up around them changes how rested you feel.
Why am I tired after a full night of sleep?
Slept a full night and still groggy? Sleep inertia — not sleep duration — is usually the real cause. Here's why it happens and how to fix it.
What's the ideal nap duration?
The science behind nap duration: why a 20-minute power nap and a 90-minute full-cycle nap both work, and why 30-45 minutes is the one length to avoid.
How to repay your sleep debt
You can't repay sleep debt in one marathon night. Here's the gradual, research-backed way to actually recover — and how long it realistically takes.
Sleep hygiene: the routines that really make a difference
Every validated sleep hygiene principle in one place: schedule, light, temperature, food, and the common mistakes that quietly sabotage good sleep.
Screens and blue light before bed: what the science says
Does blue light actually ruin your sleep? Here's what the research shows, and the practical steps that make the biggest difference.
Ideal bedroom temperature for sleep
The science of why a cool room helps you fall asleep faster and stay asleep longer, plus the ideal temperature range and practical cooling tips.
Exercise and sleep: when and how much to train
Exercise reliably improves sleep quality — but timing matters. Here's when to train, when to avoid it, and how much is actually needed.
Diet and sleep: what to eat, what to avoid, and when
How food and meal timing affect sleep quality: the foods and drinks that help, the ones that quietly sabotage your night, and when to stop eating.
Daylight saving time and sleep: how to adjust smoothly
Clock changes disrupt sleep more than most people expect. Here's exactly how to prepare for both the spring-forward and fall-back transitions.
Snoring and sleep apnea: how to tell the difference
Most snoring is harmless, but some isn't. Here's how to tell the difference, the warning signs of sleep apnea, and what to do next.
Social jet lag: the hidden cost of weekend sleep-ins
Sleeping in on weekends feels good but can create 'social jet lag' — a circadian mismatch with real costs. Here's how to catch up without it.
Best mattress by sleep position
Your sleep position determines which mattress firmness actually works for you. Here's how to match firmness and support to the way you really sleep.
Best pillow for sleep, by position
The right pillow height and firmness depends on how you sleep. Here's how to choose correctly for side, back, and stomach sleeping.
Melatonin guide: timing, dosage, and what it actually does
How melatonin actually works, realistic dosage guidance, the best timing for jet lag vs. insomnia, and when it won't help at all.
Best mattress for back, hip and shoulder pain
Waking up in pain? The wrong mattress firmness for your body and sleep position is a leading cause. Here's how to fix it.
When to replace your mattress or pillow
Most people keep their mattress and pillow far longer than they should. Here are the concrete signs it's time, by product and material type.
Anti-snoring products: what actually works
Nasal strips, mouthguards, pillows and sprays — an honest look at which anti-snoring products have real evidence behind them.
Sleep for night-shift workers, nurses and drivers
Working against your natural circadian rhythm is hard. Here's a practical, realistic sleep strategy for night shifts, rotating shifts, and long drives.
Dozofy vs Sleep Calculator
An honest comparison: Dozofy is free, has 20+ sleep tools in 7 languages with no login, vs typical single-purpose sleep calculator sites.
Dozofy vs Calculator.net Sleep Calculator
How Dozofy compares to Calculator.net's sleep calculator: a sleep-specialized toolkit with guides and screening tools, in 7 languages, vs a general-purpose calculator site.