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1. An instrument other than a watch for measuring or indicating time, especially a mechanical or electronic device having a numbered dial and moving hands or a digital display.
2. A biological clock.
v. clocked, clocking, clocks
To register or record with a mechanical device: clocked the winds at 60 miles per hour.

clock′er n.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A gene on chromosome 4q12 that encodes a ubiquitously expressed human homolog of the mouse clock gene, which forms a heterodimer with ARNTL and activates E-box element transcription of several circadian clock proteins (e.g., PER1 and PER2). CLOCK is highly expressed in the suprachiasmatic nucleus.

Molecular pathology
CLOCK-ARNTL double mutations in the PAS domains result in syngernistic desensitisation to high levels of CRY on repression of CLOCK-ARNTL transcriptional activity of PER1, disrupting circadian rhythmicity.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


A device for measuring time.

biological clock

1. An internal system in organisms that influences behavior in a rhythmic manner. Functions such as growth, feeding, secretion of hormones, the rate of drug action, the wake-sleep cycle, the menstrual cycle, and reproduction coincide with certain external events such as day and night, the tides, and the seasons. Biological clocks appear to be set by environmental conditions in some animals, but if these animals are isolated from their environment they continue to function according to the usual rhythm. A gradual change in environment does produce a gradual change in the timing of the biological clock. See: circadian; maladaptation to night work; zeitgeber
2. A colloquial term for the decrease in fertility that accompanies aging, particularly as women approach the age of 35.
Medical Dictionary, © 2009 Farlex and Partners

Patient discussion about clock

Q. How do you wake up in the morning if your narcolepsy is so severe you can't hear the alarm clock, phone ring? biggest problem is sleep paralysis, can't wake up. Late for work, everything, life is suffering because of severity. Have tried ritalin, natural supplements, hypnosis therapy, Provigal, antidepressants, nothing seems to work. Employer thinks it's an excuse, friends are irritated, I'm at my wits end. Life is spent sleeping more than awake.

A. Narcolepsy cannot yet be cured. But EDS and cataplexy, the most disabling symptoms of the disorder, can be controlled in most patients with drug treatment. Often the treatment regimen is modified as symptoms change. For decades, doctors have used central nervous system stimulants-amphetamines such as methylphenidate, dextroamphetamine, methamphetamine, and pemoline-to alleviate EDS and reduce the incidence of sleep attacks. For most patients these medications are generally quite effective at reducing daytime drowsiness and improving levels of alertness. However, they are associated with a wide array of undesirable side effects so their use must be carefully monitored. Common side effects include irritability and nervousness, shakiness, disturbances in heart rhythm, stomach upset, nighttime sleep disruption, and anorexia. For full article: Hope this helps.

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References in periodicals archive ?
Islamabad [Pakistan], July 11 ( ANI ): As the clock ticks down towards the general elections in Pakistan scheduled on July 25, many opposition leaders in the country accused the Pakistan Army of attempts to rig the elections and swing it in favour of certain political parties like Imran Khan-led Pakistan Tehreek-e-Insaf (PTI).
And, alas, it remained just that, as the clock ticked down to zero before we could complete the puzzle.
As the clock ticked down Roy Hodgson's team were holding on to a 1-0 lead against Everton courtesy of Chris Brunt's penalty after Peter Odemwingie had been brought down.
"We've discovered that we can control one of the key molecules involved in setting the speed at which the clock ticks and in doing so we can actually kick it into a new rhythm," he added.
His agents want time to investigate his affairs as the clock ticks down on a deadline for the lightweight star to repay pounds 19,000 in fees.
As the clock ticked down, news ticker-taped across the bottom of the screen from the various 'constituencies'.
As the clock ticked on negotiations, Ratner gave in to the MTA's demand that he increase his bid, doubling it to $100 million.
I had stonewalled my dear partner for weeks on our operational readiness prep, but as the MSNBC countdown clock ticked down to just how far Cher has turned back time, I relented, and we followed the orders of Homeland Security Bear Tom Ridge.
BOOKMAKERS are bracing themselves for the stream of World Cup bets to turn into a torrent as the clock ticks down to the opening match on Friday.
Ayew picked up a swift booking for clipping an Evian defender in the 74th, only to repeat the feat just after play had restarted and received his marching orders as the clock ticked over into the 75th minute.
But the Villa boss could take some tips from his Wolves counterpart and close friend Mick MCarthy when it comes to wheeling and dealing at Villa Park as the clock ticks down.
CARLO ANCELOTTI has insisted he does not need to justify his record as Chelsea manager as the clock ticks down to what appears the end of his Stamford Bridge career.