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Monitor Lizard: Should Heat Lamp Be Off at Night?

By: Dr Gareth Evans - Updated: 13 Apr 2015 | comments*Discuss
Monitor Heat Lamp Lighting Thermostat


I have an Ackie monitor lizard and because they come from the deserts of Australia and at night it can become quite chilly, I was wondering could I turn the light off. At night he usally retreates to the cooler end of the cage anyhow.

(L.W, 24 April 2009)


The answer to your question really depends on the type of set up you’re using. If the heat lamp is the sole source of warmth, it wouldn’t be advisable to switch it off – no matter how much he seems to favour the cool end.

However, assuming you have other means of warming your vivarium, such as under tank heat mats, ceramic heaters, hot rocks and the like, and the heat lamp is simply providing a basking hot-spot – which, of course, is the ideal arrangement – then there’s a lot to be said for letting it go properly dark at night. The drop in temperature that this brings also helps mimic wild conditions.

Controlling Day And Night

Many reptiles benefit from a near-natural cycle of day and night, particularly if breeding is planned; the trick is to invest in some good environmental control and buy the very best quality thermostat that you possibly can. After all, it’s the only thing that stands between your pet getting cooked or chilled – and you’re asking it to switch your heating system on and off countless times a week to maintain the ideal conditions for your lizard, so there’s no getting around the fact that quality counts!

Dimmer-stats are a brilliant choice if you’re using spot lamps; they work by gradually reducing the current flowing to the lamp once the pre-set temperature has been reached. This has two big benefits – firstly it stops the abrupt “on-off-on” which can reduce bulb life and secondly, it’s much kinder on the vivarium’s inhabitants, since they have a chance to adapt to the changing light levels, rather than being suddenly blinded or plunged into darkness.

For the absolute last-word in environmental control, however, you have to go for one of the latest, state-of-the-art dual temperature thermostats, which allow you to set different temperatures for day and night. Couple this with a timer to manage day and night length and your monitor will enjoy the most natural conditions it’s possible to get.

As a quick aside on “natural conditions” for this species – do bear in mind that they aren’t exclusively desert dwellers, inhabiting a variety of habitats in their natural range across most of tropical and sub-tropical northern Australia, except eastern Queensland. Although it’s true that they are often found in arid, rocky areas, in some places they happily take to the trees!

You’ve chosen a fascinating species of lizard to keep. The Ackie Monitor Varanus acanthurus – also known as the Spiny (or Ridge) Tailed Goanna and occasionally the Dwarf Monitor on account of its size – has become incredibly popular in recent years and they’re such active and engaging creatures that it’s not hard to see why.

The bottom line is, make sure you have the best system you can afford to maintain your pet’s ideal environment and you can safely leave him in the dark!

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