So if you regularly find yourself glazing over mid-afternoon and your boss hasn't warmed to your suggestion of daily siestas what can you do?
Stay hydrated - fatigue is often due to dehydration so drink a large glass of water 15-20 mins before you have your lunch and another one an hour after you're lunch.
Skip the wheat - wheat has a sophoric effect on alot of people, so even if you're not gluten or wheat intolerant it's worth avoiding wheat at lunchtime if you get post-lunch snooziness. Instead have new potatoes, brown rice, quinoa, pulses, oat cakes, rye bread or spelt pasta which is an older variety of wheat grain that is less problematic. EAT does a good wheat-free bread to go with it's soups and has a different wheat-free sandwich each day.
Skip the sugar - avoid sugary sauces or condiments (vinaigrette, ketchup, salad cream) on your lunch as well as puddings, fruit yoghurts or chocolate bars. These, along with refined carbohydrates (white bread, white rice, chips white pasta) and caffeine, may give you a temporary energy boost but this is usually followed by an energy crash. If you usually have a pudding or espresso after lunch switch it for a herbal tea, natural yoghurt, some fresh berries or even a square of dark chocolate.
Don't eat too much - if you eat a large meal blood flow will increase to your gut to help digestion leaving less blood, and therefore oxygen, for your brain bringing on fatigue. Aim for equal portions of vegetables/salad, protein and low GI carbs, each the volume of your fist. The low GI carbs will keep your metabolism fired up whilst the protein will encourage a slow release of energy avoiding the chance of a post-lunch crash.
Move! - If you sit still at your desk all day your metabolism will gradually slow down making you feel more fatigued so make sure you move at lunchtime. If you can go to the gym that's great but even a 20 minute walk outside will be beneficial. Also get up from your chair every hour and have a wander round the office.
Have a rest. Even if your boss doesn't approve of cat napping at the desk make sure you take a ten minute mental break. Staying focused and alert at work is pretty draining but you can counter this by giving your brain a rest. Either at your desk or in a breakout area stop working or reading and let your mind wander. Take some deep breaths and look out the window. If you can't do this at your desk pop outside for ten minutes and chill in the fresh air.