Time flies, the old man cried, as the alarm clock struck him on the back of the head.  For the elderly, time does indeed fly; not just the clock but the days, the weeks, the years.  Time seems to shorten, to press in on itself, as we get older.

But for the young, a week can last forever.  Remember how we measured our age in fractions of years.  ‘I’m seven and a quarter’, I’d reply if asked.  And that 13 weeks I boarded at school felt like 13 years.  Mathematicians have suggested that our perception of time is relative to the duration of life.  A year is 10% of our life when we are 10, but only 1% when we are 100. 

Personal time is perceived according to what new happens.  For children, the milestones are much closer. Their days are so packed with novelty, life is a constant stream of stimulation; their attention span so short that expectation seems endless.  As we get older, and accumulate responsibilities, the thrill of anticipation is replaced by the burden of obligation. There is little novelty, just more associations to work through, organise and file away. Too much to do; too little time!  With the end on the horizon, there is neither time nor inclination to look forward, so we tend to look back, reminisce, regret a bit and try to put it right. Events and thoughts collapse in on each other until time itself is confused. 

Although our perception of time passing can alter through life, our body has a remarkable ability to mark time. It knows exactly when it’s time to go to sleep, time to eat and time to defaecate, and when we change time zones, it is some time before this body clock can be reset.  So.do we have some kind of accumulator in our brain that records the oscillations of temporal neurones, or the beats of the heart?  Probably not!  Nobody has identified a cerebral clock, but neuronal and hormonal activity is responsive to environmental cues or zietgebers like day/night cycle, day length and temperature.  So while real time is relatively static in our bodies, our perception of time is elastic.  When I am running, the same route goes much more rapidly if I am in a relaxed meditative state than if I aware of my performance, even though my pulse rate is much the same.  Time is like a river; the flow may be constant, but the calms, rapids and waterfalls of our thoughts can make seem to slow it down or speed it up.   

It has been suggested that our perception of time depends on our degree of arousal.    During extreme arousal, time slows down and intensity of experience is magnified, our memory expanded.  The more energy the brain spends in representing an event, the longer it lasts.  We can get more done in the morning when our level of arousal is at its optimum.

Think of how slowly time goes during a crisis. If we are going to crash, everything seems to go into slow motion. You have an argument with your lover and then part; you remember every word, every gesture, every look. Time dilates  Psychologists call this amydala memory.  When the panic button is pressed, the brains cine film speeds up.  If you’re laying down a lot of memory, time goes by a lot more slowly, but does it just seem that way in retrospect because there’s more to play back? 

Generally time passes much more slowly if you are waiting for something, but that too depends on your perspective. Take two men at a football match. The score is 1-0. There are ten minutes to go.  To the one whose team is ahead, that ten minutes is an eternity of dread, but to the others desperation to score accelerates the final whistle.

It would seem that our perception of time is an emotional quality.  Time is suspended when you are in the thrall of love, but if you know you must part, then it speeds up alarmingly.  Samuel Johnson said that there is nothing like a hanging to concentrate the mind, but he could have equally transposed ‘time’ for ‘mind’. 

So is our perception of time a factor of the emotional energy of our thoughts?  The more energy we devote to things, the more we are conscious of time. Take boredom, for example, or depression.  Boredom is not passive or boring. Far from it, boredom is an active state of anticipation and frustration; an urgent need for something to happen, a  desire to kill time and attack your situation. Similarly most depression is a highly aroused state of anxiety and despair.  Driving my car down the motorway is the most boring thing I do. A journey to London is like a trip to the moon.  But if I listen to an audio-book at the same time, then I hardly notice it.  Children (of any age) who can lose themselves in creative play are rarely bored.  Boredom more usually applies to administrative tasks that I resent, like writing a grant application, filing a report or completing the tax return. Such a waste of time! But if I am preoccupied by some concern, that anything that takes me away from it, becomes boring. Perhaps time passes so slowly for the young because their lives are so occupied by the anxious frisson of change, that for nothing to happen is intolerable.       

Time races by if we’re absorbed in a task.  It’s a form of meditation. I have spent two hours writing this article and yet it seems I have only just started. The same phenomenon occurs if we watch a good film or when we’re relaxed at a dinner party, talking to friends.  This acceleration of time is enhanced by alcohol and recreational drugs.  I can lose time having a good time. During therapy, the 50 minute hour goes very quickly when the client is engaged and relaxed, but if he’s defensive and resistant, it drags.  We can spend seven hours asleep completely unaware of time yet if anxiety keeps us awake all night,  the slow blind slither of night-time is exquisite torture.  

So how should we spend time?  Should we seek solace in creative activity and allow time to speed by unnoticed?  Or should we seek to extend it with stimulus and novelty in an accelerating desperation to avoid the end?   What is the bigger waste of time?