What is Eye Sleep, and should you be worried about it?

We’ve all woken up in the mornings feeling a bit sleepy, only to find some crusting or gunk in our eyes. Sometimes called “eye sleep”, the substance is a combination of eye debris and hardened tear film which falls into the eye’s inner corner and then dries up overnight, forming the crust. The official term for “sleep” is rheum, and it comes in a variety of consistencies and colours, depending on how much of it has evaporated overnight, and on exactly what is in it. Rheum is completely normal and is just residue from the eye’s protective process. Throughout the day, the eye’s tear film keeps the eye hydrated, and removes harmful debris and bacteria. The tear film has three components which play a vital part in ensuring the perfect level of hydration:

“Closest to the eye is the glycocalyx layer – a layer made mostly of mucus. It coats the cornea and attracts water, which allows for the even distribution of the second layer: the water-based tear solution. It might be just four micrometres thick – about as thick as a single strand of spider silk – but this layer is very important. It keeps our eyes lubricated and washes away potential infections. Finally, there is an outer layer composed of an oily substance called meibum, which is composed of lipids like fatty acids and cholesterol.” Source: BBC

When you’re awake, you blink away any excess eye discharge but this collects overnight when your eyes are closed for a long period. Further to this, sleep relaxes the meibomian gland ducts, causing more of the tear film’s oily substance to enter your eye.

What are the causes?

As we’ve discussed, eye discharge is completely normal and is something which most people experience upon waking each morning. However, if you notice a change in colour, consistency or quantity, it could be a sign that your eye discharge is occurring as a result of an infection such as:

Conjunctivitis: A common eye infection which can be viral, bacterial or allergenic, whereby the sclera becomes inflamed. One of the most prevalent symptoms of conjunctivitis is thick eye discharge, which collects along the lash lines while you sleep, and varies in colour and consistency according to the type of conjunctivitis.

Blepharitis: This condition presents itself in the form of crusting and inflammation of the eyelids, leading to sore eyes, swelling and a yellowy-green eye discharge. It can also be caused by “abnormal oil production from the meibomian glands” and the discharge builds up in your eyes overnight as you sleep.

Corneal ulcer: This is a sight-threatening infection of the cornea caused by eye trauma or a severe infection. Symptoms of a corneal ulcer are eye inflammation and redness teamed with heavy eye discharge or pus-like substance. If you are experiencing these symptoms, seek help urgently; the sooner the condition is treated, the greater the chance of saving your sight.

Dry eye: Ironically, chronic dry eye can also result in an excess of tears and eye discharge. This is because the eye senses that it isn’t lubricated enough and so goes into overdrive, producing more tears than necessary. Overnight, this can build up and solidify in the eye’s corners, leaving you with those all-too-familiar crusty morning eyes. Although not an infectious condition, severe dry eye can cause discomfort and eye discharge – but thankfully it’s easily treatable.

How to safely remove Eye Sleep

When you wake up in the mornings, it’s very tempting to rub away any sleep or gunk in your eyes, or try to pick it out of the inner corners. This is actually a risky approach, as it’s very easy to accidentally scratch your eye or the surrounding area. Depending on the severity of the discharge, you might also pull out eyelashes in your attempt to remove it. Eye sleep can also be a sign of an infection where your eyes will already be more susceptible to bacteria – so putting more germs there whilst you remove the sleep is counterproductive.

To safely get rid of any residue or discharge which has accumulated overnight, you should first wash your hands, and then use a warm flannel or compress. In severe cases, the eyelashes may be stuck together with excess rheum or discharge. If this happens, soak your closed eye under a warm, damp compress and gently wipe to remove the eye sleep. Washing your hands before and after touching your eyes should prevent the infection – if this is the cause of the discharge – from spreading to the other eye, or to other people.

When should you be concerned?

First and foremost, if you notice a significant change in your eye sleep, it’s important to get it checked. This could be experiencing more discharge than usual, a change in colour, or a noticeable change in consistency. Any of these symptoms could be an indicator that something is amiss. Other issues with your eye sleep could be suggested by:

• Sudden light sensitivity
• Red or inflamed eyes
• Eye pain
• Blurry vision

Small amounts of eye sleep are perfectly normal and should be yellowish or clear in colour. It can also be crusty and hard, more sticky and thin, or even watery. Colours like green, grey or white signal an infection and, when combined with any of the above symptoms, could be something more serious. If in any doubt, get checked by an eye doctor to understand the causes of your eye discharge.