The science behind the calculators.
Short reads on sleep cycles, blood pressure and jet lag, with the evidence in view.
- Sleep apnea: the warning signs, and why it matters for your heartObstructive sleep apnea is common, often undiagnosed and linked to high blood pressure. Learn the signs, how screening works and what treatment involves.
- How long should a nap be? The 10, 20 and 90 minute ruleShort naps refresh you without grogginess, long ones complete a full sleep cycle. Here's how to pick the right length and time of day.
- When to have your last coffee (it's earlier than you think)Caffeine lingers for hours and can cost you sleep even when you take it in the afternoon. Here's how to time your last cup.
- How much sleep do you need? Recommendations by ageExpert sleep recommendations for every age, from newborns to adults over 65, and what to do if you regularly fall short.
- Why flying east is harder (and what light has to do with it)Your body clock drifts later on its own. Flying east asks it to run earlier. Here's the clock math, and how to cheat it.
- Short sleep and blood pressure: what the studies actually saySleeping under six hours is linked to hypertension, and sleep apnea is a bigger link still. A plain-language tour of the evidence.
- Ninety minutes is a rule of thumb, not a lawThe 90-minute sleep cycle is a useful average. Here's how much it really varies, and how to find your own number.
