Half Lives of Sleeping Pills

I often get asked about sleeping pills by followers of Sleepless No More – including about their half lives and what they mean.

How long do sleeping pills stay in your system?

Can they affect me the next day, for example at work?

Do sleeping tablets affect my performance the next day at work?

The half life of a medication is the time it takes for half of the active components of the drug to go out of your system.

And when we use ‘half life’ as a measure, it doesn’t mean that you just double that figure to arrive at the time it takes to completely remove the medication from your system, because the graph is not a straight line, but a curve.

Here is a diagram that helps explain it (that is not about sleeping pill half lives, I can’t find one of them on the internet, but it will give you an idea).


On the vertical access at the left should be the percentage of the medication in your system, starting at the top, at 100% when you take the medication.  (e.g. 0.2 on the diagram would be 100% concentration of the drug, 0.1 would be 50%, and so on.)

On the horizontal access should be the time.  So if the half life is, for example, 6 hours then the point 50 on the horizontal access would be 6 hours – along the bottom.

Following this example, if the half life of a drug is 6 hours, then at 12 hours you will still have OVER 25% of the drug still in your system – it will not have totally disappeared in 12 hours.  In fact, as the diagram above shows, as the concentration of the drug reduces, the time it takes to get rid of the next half-life (or, say, “50% potency”) will actually take longer than the original 6 hours.

This becomes totally relevant to administering your medications.  e.g. if you take a tablet last night that has a half-life of 20 hours, then when you take one the next night, you are now adding on 100% dosage to the close to 50% dosage left from the night before…

Are you aware that that is what you are doing?

Did your doctor tell you about “half lives” when he gave you your sleeping pill prescription?

By the way, we are not recommending one type of sleeping pill over an other on the basis of this page/post – we are just supplying you with more information to investigate your strategies further.

Well, you know we would prefer you to investigate other methods to sleep better ….

Here are the half lives of different sleeping pills as declared on the pages of Wikipedia today – June 4, 2012:

Zolpidem (includes Ambien CR, Stilnox, Sublinox, Edluar): 2 – 3 hours half life.

Temazepam (includes Euhypnos, Normison, Norkotral, Nortem, Remestan, Restoril, Temaze, Temtabs, Tenox: 8 – 20 hours half life.

Eszopiclone or Lunesta:  6 hours half life.

Ramnelteon, Rozerem etc: 1 – 2.6 hours half life.

Triazolam, Halcion, etc.  1.5 to 5.5 hours half life.

Estazolam, etc:  10-24 hours half life.

Zaleplon or Sonata, Starnoc:  1 hour half life

Triazolam or Halcion, Apo-Triazo, Hypam, Trilam:  1.5 to 5.5 hours half life

Ramelteon or Rozerem: 1 to 2.6 hours half life

And here is some research that you might find interesting:

“All hypnotics, at some doses, produce decrements in performance the next day.  Higher doses consistently showed a decrement, and this decrement was usually persistent over the entire day.  Although long-acting drugs generally showed more performance decrement, half-life data were not consistent.”

Source:  Sedative-hypnotics and Human Performance”.  Laverne C. Johnson and Doris A. Chernik.

Be careful when looking at the half lives figures.

It appears the jury could still be out on this – some experts saying that even the short half life tablets can have serious implications – read this:


Tell us how you go with this information.