There’s nothing more frustrating than heading out with a fully charged phone to find it completely dead just a few hours later.

But you may be surprised to know that battery drain is often worsened by the so-called ‘vampire setting’ hidden deep within an iPhone.

Despite its terrifying nickname, the life-sucking feature is more blandly known as ‘Wi-Fi Assist’ and allows Apple users to hop on to mobile data when networks lag behind. 

Whether you’re streaming Netflix on the bus or downloading a file in the mountains, this can be an incredibly handy tool on the go.

However, users should be aware that it can also rapidly kill battery life, with the tool automatically enabled on all iPhones.

To see it for yourself, head to the ‘Settings’ menu before tapping on the ‘Mobile Data’ tab.

Here, you’ll see personal hotspot information as well as insights on how  data is used for different apps on the device.

The ‘Wi-Fi Assist’ toggle is located far below this, so you’ll need to scroll right to the bottom where you’ll find it located just above ‘iCloud Drive’.

If you’d like to turn this off, tap the toggle just once to turn it from green to grey – this change will save automatically. 

Wi-Fi Assist can be used for numerous apps including but not limited to Safari, Apple Music, Mail and Maps.  

While the setting can impact battery life, it’s important to note that it won’t automatically switch to ‘cellular’ if you have data roaming switched on.

Data roaming generally occurs when using a mobile phone on holiday, with the internet switching to an internet network located in whatever country you’re in. 

Wi-Fi Assist solely focuses on apps running in the foreground too and doesn’t activate programs in the background or third-party apps.

The latter can eat up large volumes of data – not only costing you precious battery life but money as well. 

‘There are two simple ways you can preserve battery life — no matter how you use your device: adjust your screen brightness and use Wi‑Fi,’ the tech giant says.

‘When you use your device to access data, a Wi‑Fi connection uses less power than a mobile network — so keep Wi‑Fi on at all times. To turn on Wi‑Fi, go to Settings > Wi‑Fi to access a Wi‑Fi network.’

iPhone owners can dim their screen brightness by accessing the ‘Control Centre’ accessed by swiping down from the top right-hand corner of a screen on newer models. 

Switching on ‘Auto-Brightness’ can help too – found in the ‘Accessibility’ tab of ‘General’ in ‘Settings’.

It is said that women are more likely to want a daughter than a son.

But mothers with multiple children, beware: a study suggests that having three daughters can lead to a significant decline in wellbeing.

Researchers combined data from two large British studies which followed participants from birth to adulthood.

Subjects were surveyed at least once every decade, reporting their levels of life satisfaction and whether they had children.

Analysis revealed that after having a third child of the same sex, parents experienced a significant decline in their wellbeing compared to those who had a third child of the opposite sex to the first two.

This effect lasts for a decade, they discovered, and was entirely driven by mothers who had a third girl.

The researchers, from the London School of Economics and Political Science, also found that parents who had two children of the same sex were more likely to try for another child, and do so faster than those who already had a boy and a girl.

Lead author professor Paul Dolan said: ‘Parents who have two children of the same sex are more likely to try for a third in the hope that they will ‘win’ the birth lottery.

‘Our data suggests that the disappointment is mostly from mothers with two girls not having a boy, as opposed to mothers of two boys not having a girl..’

He reported his findings in a study titled: ‘All we want is a healthy baby – well, and one that is the opposite sex to what we have already.’

It reads: ‘We all know families with three boys or three girls.

‘Did they go on to have three children in the hope that the third child would be the opposite sex to the first two?

‘Are they disappointed when they have another child of the same sex?

‘We show that… having three children of the same sex negatively affects life satisfaction. This effect is driven entirely by mothers who have a third girl and lasts for 10 years after birth.

‘It seems that mothers with two girls are hopeful that they can have a boy and are disappointed if this does not happen.

‘We conversely found that having two children of the same sex boosts subjective wellbeing.’

Professor Dolan said the reason behind his findings could lie in mothers not wanting too many females in a household.

‘One possibility would be that this reflects the superior earning power of boys, which persists despite progress in gender equality,’ he wrote.

‘This would be a milder version of the preference observed for boys in developing countries.’

The research was published in Elsevier’s Journal of Behavioural and Experimental Economics.