Time in bed versus time asleep: your seven hours might be six

The sleep checkbox asks for seven or more hours. Almost everyone ticking it is measuring the wrong thing — the time between lights out and the alarm, rather than the time actually spent asleep.

The difference has a name, and for most people it's between fifteen and forty-five minutes a night.

What sleep efficiency is

Sleep efficiency is the proportion of your time in bed that you spend asleep. It accounts for how long you take to drop off, plus the brief awakenings through the night that you mostly don't remember.

Even good sleepers don't hit 100%. If you're in bed for seven and a half hours at a fairly typical efficiency, you're closer to six and a half hours of sleep — which is under the threshold the American Academy of Sleep Medicine and Sleep Research Society recommend for adults.

• Time to fall asleep: often fifteen to twenty minutes for a normal sleeper
• Brief night wakings: usually not remembered, still deducted
• Early-morning wake before the alarm: counts against you
• Add fifteen to thirty minutes to time in bed to cover the gap

Why it matters more during a cut

Because the deficit is already pulling on the same levers. Short sleep raises appetite and perceived effort, both of which are already elevated by eating less and training more.

So the person most likely to be quietly under-sleeping — someone in week three of a hard program — is also the person for whom the last forty minutes matters most.

How to check the box honestly

If you're tracking with a watch or a ring, use the sleep-duration figure rather than the time in bed. Those devices aren't laboratory instruments and they'll estimate imperfectly, but they're consistent enough to show a trend, which is all you need.

If you're not tracking anything, use the simplest correction there is: aim for seven and a half to eight hours between lights out and the alarm, and treat that as your seven.

Fixing the gap at the front, not the back

• Move lights-out earlier by fifteen minutes rather than trying to fall asleep faster
• Keep the wake time fixed, including at weekends — it's the anchor for everything else
• If you're awake more than twenty minutes, get out of bed and do something dull in low light
• Persistent trouble falling or staying asleep for weeks is worth raising with a clinician, not solving with a tracker

“Seven hours in bed is not seven hours of sleep, and only one of those recovers you.”