Although I can't tell you what DHL is like to work for, having been a creature of the night for the last 7 years or so in a non-flying job, I'd just like to make a few points about working nights.
The main drawback is that this is difficult to integrate with any sort of normal family routine, especially for those with young children, who generally end up with the regular half-day upset of their circadian rythm when they take time off, which is then reversed when they go back to work. They are effectively subjected to being more or less constantly "jet-lagged" to some degree. This is definitely not good for health or the ability to function properly at home or at work.
For those of us without such responsibilities, there is no reason for this to be a problem at all if we are prepared to stick to roughly same routine associated with a normal night shift pattern during our time off. Such a lifestyle has in fact got a lot going for it...
It's not the usual sort of rush-hour rat-race hassle just getting to work for a start. This theme continues throughout the night - instead of the relentless palaver associated with daytime competition to utilise transport, communication and social infrastructures of every kind there is a generally more relaxed working environment with easier social interaction. I'm convinced that people are nicer to each other on the night shift.
Some of the very early mornings in summer are also the most heart-achingly beautiful time to be alive - most day shift bods rarely get the opportunity to experience this apart from farmers, anglers, bakers, posties and other such early risers.
However, even they don't have the privilege of sloping off home to sleep through the mundane rigour of British mornings - a time when no-one appears to be at their best in any case. Mornings are boring for most folks, who are really not interested in anything other than getting through their day until about mid-afternoon.
By getting up in the afternoon one has a few hours to interact with the day shift masses while they are beginning to relax a little and re-discover their sense of humour (which is probably due to their increasing proximity to knocking-off time). This is therefore the best time of the day for any kind of half-decent non-robotic service from shops, banks, or any business you may have to deal with over the phone for example.
For me this is also that part of the day during which I might do a spot flight instruction with a student who is generally happy-as-Larry to be commiting aviation instead of working.
During his time off, a night shift worker can be up by lunchtime without too much difficulty, and could for example share "brunch" with family or friends with the best part of the day remaining do with what he will. There is also the advantage of rarely being the first to fade during an evenings socialising, although a slightly earlier rise will mean that he can easily be asleep by the middle of the the wee small hours if he has nothing better to do.
Human beings are really very adaptible and the only health problem such a lifestyle should cause you is perhaps a touch of bad skin in winter due to lack of daylight. Although I have heard that night-shifts can cause problems for female fertility, I would not be surprised if this only relates to those who are likely to experience any of the other health problems relating to continuously disturbed sleeping patterns - stress, blood pressure, digestion etc.
If as a night-shift worker you are disciplined enough to stick to the same basic sleep routine, and organised enough to squeeze everything you need to into the remaining two-thirds of your life then there's no reason why you shouldn't be at least as healthy and happy as you would be if you worked days - and possibly even more so.
For example, a day-shift worker who regularly indulges in a busy social life over the weekend could concievably wreak more havok to their circadian rythm, and long-term health.
DHL would appear to be about the only outfit which offers UK based crews the opportunity to work constant nights flying exclusively SLF-free big shiny jets.
YOU LUCK-EE, LUCK-EE B757ARDS !!!
