every fourth hour

USAGE SUMMARY

The phrase "every fourth hour" is correct and usable in written English.
It is used to express something that repeats or happens in regular intervals. For example: "The train departs every fourth hour."

✓ Grammatically correct

Science

News & Media

Formal & Business

Human-verified examples from authoritative sources

Exact Expressions

4 human-written examples

In addition, blood pressure was measured regularly (at least every fourth hour) during the first 24 hours.

Critical Care Medicine

Ultrasonography was performed every fourth hour from about 20 h after the onset of oestrus and until ovulation had occurred.

Acta Veterinaria Scandinavica

All patients had regular measurements of serum sodium, potassium, ionized calcium, pH, pCO2 and bicarbonate either from an arterial line or from a central venous line before the start and regularly every fourth hour all through the CRRT treatment during 1, 2, 3, 4 and maximum 5 days.

Acta Anaesthesiologica Scandinavica

The recommended number of days in hospital after a normal birth was 7 to 8. At that time, postpartum care was characterised by strict and rigid routines, such as scheduled breastfeeding every fourth hour during daytime, and supplements or other mothers' breast milk in the nursery at night.

BMC Health Services Research

Human-verified similar examples from authoritative sources

Similar Expressions

56 human-written examples

CSF and blood samples were obtained every second hour during a 16-hours study period and were analyzed for bacterial concentrations by quantitative cultures (lower detection level: 50 CFU/ml) and WBC on an automatic cell counter (Swelab, Åstad, Sweden).

BMC Infectious Diseases

Consecutive sampling of aldehydes every eighth hour as well as total aldehyde sampling was performed during the first 5 days after application of the paints.

Industrial Crops and Products

N = 34 professional driver students drove in a high-fidelity driving simulator at 80 km/h for 55 min every third hour during 36 h of sustained wakefulness.

Accident Analysis & Prevention

Eight blood samples were drawn each day (every third hour) on 8 days of the protocol and analyzed with respect to IL-6 and TNF-α.

Brain, Behavior, and Immunity

The occurrence of aggressive behaviour, play behaviour and synchronous resting was recorded throughout the day (i.e. every third hour for 15 min during 24 h) on day 1, day 5, day 19 and day 33 after mixing.

Applied Animal Behaviour Science

Every third hour, you squeeze a Monopoly-race-car-sized amount onto the tips of your fingers (right hand), and then dab your ends with it.

The New Yorker

Bar graphs showing concentrations of serum triglycerides and plasma EVs before (fasting) and every second hour after ingestion of a standardized high fat meal (panel A, bar graphs are means with 1 standard deviation, ***p < 0.0001 from fasting levels).

Nature

Expert writing Tips

Best practice

When describing a schedule or protocol, use "every fourth hour" to clearly indicate events that occur regularly with this specific interval.

Common error

Avoid using "every fourth hour" when you actually mean 'for four hours'. The first indicates a recurring event, while the second indicates a continuous period.

Linguistic Context

The phrase "every fourth hour" functions as an adverbial of frequency, modifying a verb to specify how often an action occurs. Ludwig AI confirms this usage in the provided examples.

Expression frequency: Rare

Frequent in

Science

75%

News & Media

12.5%

Formal & Business

12.5%

Less common in

Wiki

0%

Encyclopedias

0%

Reference

0%

Ludwig's WRAP-UP

In summary, the phrase "every fourth hour" serves as an adverbial of frequency to denote occurrences at four-hour intervals. While grammatically correct, as confirmed by Ludwig AI, its usage is relatively rare. It is most frequently found in scientific and medical contexts, where precise time specifications are crucial. When using this phrase, ensure that the context requires a recurring action at the specified interval, and avoid confusing it with a continuous duration. Consider alternatives like "once every four hours" or "every four hours" for simpler phrasing.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

every 4 hours

Uses a numerical abbreviation for 'four'.

once every four hours

Rephrases the frequency explicitly, using "once" to emphasize a single occurrence within the four-hour period.

each fourth hour

Adds emphasis on each individual instance of the fourth hour.

at four-hour intervals

Similar to the previous phrase, this highlights the regularity of the spacing.

every 240 minutes

Expresses the same duration in minutes for increased precision or a different perspective.

every four-hour interval

Emphasizes the interval itself rather than the action occurring within it.

on a four-hourly basis

Uses an adjectival phrase to describe something that happens with the specified frequency.

every quarter of the day

Changes the focus from hours to a division of the day, implying a similar regular interval.

four times a day during specific hours

Indicates the total frequency within a day while specifying these measurements only take place in the period indicated.

every fourth of the hours

Focuses the division and emphasizes the distribution in time, in contrast to other metrics.

FAQs

How can I use "every fourth hour" in a sentence?

You can use "every fourth hour" to indicate an action or event that occurs regularly with a four-hour interval. For example, "Blood pressure was measured "every fourth hour" during the first 24 hours."

What's a simple substitute for "every fourth hour"?

A simple substitute is "once every four hours", which explicitly states the frequency of the event.

Is it correct to say "every four hours" instead of "every fourth hour"?

Yes, "every four hours" is more common and equally correct. Both phrases indicate the same frequency.

What does "every fourth hour" imply about the other hours?

It implies that the action or event occurs only at the specified hour within each four-hour block, and not during the other hours.