Underlying physiological reasons such anemia, hypothyroidism and rheumatoid arthritis are some things that may cause exhaustion. It  is also important to make sure that the exhaustion is not caused by overwork, excessive drinking, insomnia or that you're recovering from a bacterial or viral infection that would make you tired.

40% of the cases of tiredness/exhaustion cases are caused by lifestyle and psychological reasons. If these are recognized they can be worked on. It's a good idea to start with the working environment, is it too noisy, are you sitting too close to the photocopiers, do you use the computer all day, are you sitting in a good chair,  is the lighting to dim, are you sitting close to the air vents? 

Essential oils have historically been used for exhaustion, tiredness, and fatigue for a long time. The oils recommended for exhaustion can be used in all the usual way. At the bottom of this post you'll see some links to tips on how to use essential oils.

Worwood recommends the following:

Essential oils to help in cases of exhaustion:

Bergamot, eucalyptus globulus, eucalyptus radiata, rosemary, black pepper, cypress, grapefruit, ginger, marjoram, frankincense, lemon, cardamon and pine.

As you notice, some oils listed are traditionally used to calm, but Worwood says that overstimulation in tiredness can result in increased tiredness instead of relief from it.

Essential oils to help in cases of nervous exhaustion:

Juniper, rosemary, Roman chamomile, clary sage,  lavender, petitgrain, orange, neroli and marjoram.

Essential oils to help in cases of general mental fatigue:

Basil, Eucalyptus Piperata, Eucalyptus Citridora, lemon, rosemary, peppermint, petitgrain,

Essential oils to help in cases of mental tiredness:

Marjoram, peppermint, clary sage, rosemary, lavender and grapefruit.

Essential oils to help in cases of intellectual fatigue:

Rosemary, cypress, black pepper, ginger, peppermint, lemon, grapefruit and basil.