To get a meaningful answer to you question can we ask you to provide more details? Everyone's pulse rate varies not only throughout the day, but also according to what stress (or load, both physical and mental) the body is experiencing. As well as this, no two people's pulse rates are the same, so there is no "normal" . So, what we need to know is how much your pulse rate varies over the day, and how far from your median 'REST' rate the 140 bpm is. And of course, whether you are doing something at about 5 pm each day that explains it. Can you take several readings? At (say) just before rising? 10 am? 11.30? 2 pm, 4 pm? 5, 7, 10, and midnight? That will allow sensible analysis of your profile to be made. 140 bpm is well outside the distributional "average" resting rate, but is not necessarily abnormal for many conditions. Are you otherwise fit and healthy? - What's your age?