Can't get to sleep: tired is one thing, sleepy another.

It's 11pm, and you were nodding off over dinner. You turn out the light, your mind starts up again and you think: I can't get to sleep. Tomorrow's meeting, that remark you regret.

I hear this a lot from the business owners and managers I work with. The next night many of them go to bed earlier and lie there, trying. It usually gets worse. You're tired, but you aren't sleepy.

Tired or sleepy: how to tell

• You drop off on the sofa, not in bed. Get into bed and you're wide awake.
• You check the time and do the sums. After that it's often anxiety about not sleeping that keeps you up.
• The jolt as you go under. That twitch is you entering sleep, and it's common.

Why can't I get to sleep?

Because falling asleep takes three things at once. Tiredness covers only one.

The need for sleep. From the moment you wake, your brain builds up a substance that pushes you towards sleep. Coffee only masks it, and a long or late nap uses some up.

A body that cools down. To drop off, your core temperature has to fall a little. Heat leaves through your hands and feet, so cold feet or a warm bedroom usually slow things down.

Revs that come down. After an argument or a difficult email, your body can need half an hour to an hour to settle, and willpower alone won't shorten it. Close the laptop at 10:45 and at 11 the engine is probably still running.

How to fall asleep fast

By day, light and movement. With age your body makes less of its night-time hormone, so a clear contrast between bright days and dark evenings helps. Get outside in the brightest hours, between ten and two. And move until your heart rate climbs, for twenty minutes or more. Done regularly, it tends to bring sleep on sooner. Last coffee straight after lunch.

Fixed alarm, weekends included. When you get up usually matters more than when you go to bed. Go to bed when you're sleepy.

A hot shower, an hour to an hour and a half before. It sounds backwards. Hot water draws blood to your skin, so when you step out your body sheds heat and cools faster. Bedroom between 18 and 20 degrees, and warm your feet if they're cold.

A slow last hour. Lights low and a paper book, even a dull one. First write down what's still open and tomorrow's first step. Often it's the unfinished list that keeps your head switched on.

In bed, if sleep won't come. Turn the clock away. Clock-watching feeds anxiety. Breathe slowly. Two breaths in through your nose, the second short, then a long one out through your mouth. One to three times. Still awake after twenty minutes or so? Get up. Another room, low light, something quiet. Go back when your eyes are closing. Repeat if needed. Lie there forcing it and your brain may learn that bed is where you stay awake.

Start with one thing, whichever costs you least, and add the rest once it's a habit.