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The problem with all night shifts, regardless of shift length, is that they don’t match up with the lifestyles of the rest of the world. On nights, you are expected to be awake when everyone else is asleep and then you are to sleep when everyone else is awake. A pretty tall order.

Most shiftworkers on nights report getting less sleep than on any other shift. There are several reasons for this. First of all, if your circadian rhythms are set to keep you awake during the days and asleep at night, they will actually be working against you. Secondly, we don’t like to sleep during daylight hours because we have family and social opportunities that we don’t want to miss. Finally, there is the sleep environment itself. It is hard to completely isolate yourself from the lights and sounds of the day when you are trying to sleep.

All of this means we sleep less when working nights. The problem with 8-hour shifts is that there are a lot of them. This generally means that the more shifts in a row you work, the farther you fall behind in your sleep. At the same time, the more shifts in a row you work, the more able your body is to match your circadian rhythms to your new sleep pattern, thus improving sleep. So, on the one hand, more days in a row means more fatigue while, on the other hand, more shifts in a row means better sleep – eventually.

Now let’s consider 12-hour shifts. There are a lot fewer shifts to work if you switch from 8-hour shifts to 12′s. This generally means that you will only be working 2-4 night shifts in a row instead of 5-7 8-hour shifts in a row.

One popular schedule pattern is the 2-3-2. On this schedule, you work 2 or 3 nights in a row before getting a 2 or 3 day break. The good news is that you don’t work too many nights in a row so you never fall too far behind in your sleep. The bad news is that since you work fewer nights in a row, you never get a chance to adjust to the shift. Additionally, you only have a few days off between shifts (on some patterns) which means you may have trouble readjusting to days (on your days off) as well.

If you go to a 4-on-4-off pattern, you will work more nights in a row and thus, fall farther behind in your sleep. However, the more nights in a row means (1) your body will adjust better to the night shift than if you worked fewer nights in a row and (2) more in a row means fewer times that you need to readjust to nights when you return to work and finally (3) you have 4 days off in a row which gives you a chance to adjust to days on your days off.

A 2-3-2 pattern means that you have to adjust to night shifts 78 times a year. A 4-on-4-off pattern only has 46 adjustments to nights in a year.

So, what is best for you? It comes down to your own behavior. If you find that you cannot adjust to nights at all, it is better to work fewer night shifts in a row to limit your accumulated sleep debt. If you adjust easily to nights, work more of them in a row to minimize those difficult first couple of days that we all go through when making the adjustment.

Lean manufacturing is one of those rare production crazes that actually works. People that have never heard of it might immediately think it implies reducing the size of the workforce. This is simply not the case.

Lean manufacturing  means to produce with the goal of zero waste.  So the question is, “What is waste?”  Waste can be inventories sitting in the warehouse not doing anything. Waste can be a downstream work center waiting while upstream work centers are falling behind. Waste can be time spent looking for tools because the workspace is a mess.

If it is not adding value, it is waste.

The shift work structure used in a Lean Manufacturing environment is extremely important. It would be a wild coincidence if every work center needed exactly the same amount of coverage every day.

In actual practice, companies try to do just that. They put everyone on the same schedule and then hope that the workload balances out. When it doesn’t, waste is created either by high overtime, high inventories or idle work centers.

Lean manufacturing works. Make sure your shift schedule works as well.

There is not a perfect answer for this question. Most 8-hour operations have the day shift start between 6:00 am and 7:00 am. The afternoon shift would start 8 hours later; the night shift, 8 hours earlier. for 12-hour shifts, the start times tend to start about 30 minutes earlier. So, if you are on an 8-hour schedule that has a day shift that starts at 6:30 am, expect the workforce to want a 6:00 am start time for 12-hour shifts.

Our research has shown that employees starting at 7:00 am get about 20 minutes more sleep per night than those starting at 6:00 am. Before you run out and change your schedule, consider the following: (1) shiftworkers are typically locked into whatever start time you currently have. They will resist change. (2) The later the day shift starts, the later the night shift gets off. This is the trade-off. Ideally, a night shift would end early enough to allow the night shift to get home before the sun comes out. This means getting off earlier rather than later.

Overtime is a topic that I could write a book about and still only hit the highlights. My intention is to, from time to time, post something about overtime. In this way, we can cover it in small, manageable chunks.

Let’s make it simple to start with.

The Good: Overtime represents a set of trained labor hours that can be used in increments needed to exactly match the job at hand. Cost-wise, overtime probably costs about 10% more than a fully loaded straight time hour. However, since it tends to be more productive, the cost per hour can actually be significantly lower.

The Bad: If there is too much overtime, the workforce will complain about not having any time off. If you try to reduce overtime, they will complain about lack of income opportunities.

The Ugly: High overtime can increase fatigue, turnover, absenteeism and safety incidences.